Auto FE - It's all about driving style [ Archive] - GasSavers.org - Helping You Save at the Pump

OK. I have been spending a lot of time trying to figure out how to boost the mpg in my 2000 Honda Civic Coupe EX w/ auto transmission for the past month. My whole goal is to save money so spending money on major mods is just not an option.

Outside of boosting the PSI in my tires from 35 to 45, I haven't changed anything to the car in the last month. So I have been focusing a lot on what options I have on driving style. Obviously with an auto transmission, coasting with the engine off just isn't an option. So I have been playing around with my techniques and thought I would share with the group what I have learned so far.

This is for the newbies to this site. I am sure the veterans are all aware of what I am about to list. Most of these relate to highway driving w/ 65 mph speed limits.

1) Reduce Rolling resistance - bump up the PSI in the tires to help reduce rolling resistance and keep an eye on the pressure in each tire. I have two tires that seem to leak air very, very slowly when pumped up to 45 psi.

2) Downgrade Slope Multiplier w/ Neutral Coast - Accelerate quickly down the downhill slope to 5 or 7 mph over the speed limit prior to going up a hill. This uses gravity as a multiplier to boost your mph acceleration with less gas. You can then wait until you have reached the steepest grade uphill and shift to neutral and coast until you are about 5 mph under the speed limit and then add the gas. Be sure to maintain speed with the gas going up hill and not try to accelerate uphill. The less gas you use uphill, the better your FE.

3) Safe Drafting- Never go down the road at highway speeds without trying to be behind someone to catch a bit of draft advantage. Even if it is a pickup truck or minivan, there are advantages to this. Minivans are good because you can often see straight through the minivan windows to see the brake lights of the vehicle in front of it. This gives you more time to brake if traffic slows down quickly. If you can get behind a semi w/ box trailer, your drafting will be even better. I accelerate up close behind the semi (within 20 ft or so) and then shift to neutral and coast for a while. This helps a bunch but this opportunity isn't always available. It also removes the ability to coast uphills as mentioned in #2 above.

4) Side Roads / Access Roads - Most of the time, these roads are much less traveled. If there is a way to drive on these roads at about 10 mph less than the highway or regular route you take, that decrease in speed will help with FE. The trick is avoiding or timing stop lights. That all comes from knowing your route really well and deciding if it really helps or not. With these open stretches with less traffic, you can also add other techniques such as accelerating downhill and neutral coasting up hill. Drafting won't be as much of a benefit at slower speeds.

This is all I have so far but thought I would share with the group. It is so hard to find things that can be used for vehicles with auto transmision that I really thought I should share with the group. These techniques are working for me as I have been able to boost my mpg from 33 to 40 in the last 30 days.

If you have other driving techniques that also help, by all means, add them to this thread. I need more ideas.

I also suggest getting a scangauge. It'll let you see, in real time, what helps and how much it helps. It really helps you optimize your driving style. In a year, it's saved me enough to pay for itself, and now enough to buy another if I wanted.

so what speed do you reccomend... i just got in to a civic from a crv and i am seeing that the fe speed is not what it was for my crv...

If it's an automatic, whatever speed will keep it in top gear, and just a little above that. Probably 45-50 mph.

Manual - the best speed is slower. ;) Keep the rpms down and use moderate throttle.

I agree with PaleMelanesian. It does seem that 45 - 50 seems to be about right for my 2000 Civic. Even if you don't have a ScanGauge (which I don't), you can keep an eye on your RPM gauge and pay attention to when your auto trans shifts gears. With practice, you can learn how to keep it in the lowest range of your top gear for best efficiency.

One correction to my original post, I have since abandoned trying to draft behind trucks, etc. I usually have to run at a faster speed to stay in the draft and it is way too much work to be in that zone and be ready to brake if needed. I have found it is better to run at 63 mph in a 65 and let people fly by me instead. I get much better gas mileage that way and run at a little lower RPM too.

By the way, take a look at my garage log to see the improvements from perfecting these driving practices over the last several months.

Hey, Scott! That's a nice bump in your gaslog chart! Keep it up!

Hey, Scott! That's a nice bump in your gaslog chart! Keep it up!

Pale,

Don't let that last log entry fool you! That was only 3 days of driving over the weekend with perfect driving conditions to hit over 49 mpg.

It did wake me up to the potential of the car though and the impact of driving style on fuel efficiency. I do think that with my daily commute FE will end up around 39 mpg as I continue to put into practice what I am learning.

When i first start my old 94 intrepid i put it in gear and just let to go without stepping on the gas pedal. The read out on the gauge that came with the car for mpg starts climbing up to 14 to 18 mpg as i gain speed still not stepping on the gas. It is only going 15 mph but at 18 mpg it is very efficient until warm up and then i start using the gas very gently. This may help you when you start to go in your car.

When i first start my old 94 intrepid i put it in gear and just let to go without stepping on the gas pedal. The read out on the gauge that came with the car for mpg starts climbing up to 14 to 18 mpg as i gain speed still not stepping on the gas. It is only going 15 mph but at 18 mpg it is very efficient until warm up and then i start using the gas very gently. This may help you when you start to go in your car.

1cheap1,

Thanks. That is interesting. I live on a deadend road so I have a 1/2 mile to go as fast or as slow as I want with no traffic problems. I will hav to try this. It may not be as much of an issue in the warmer summer months as the car will warm up faster or even start out somewhat warm.

Hi Scott - good going.
I've been hypermiling my auto-tranny car for a bit more than a year now and my bag of tricks is just about identical to yours. I drive mostly highway too.

I also found that drafting is good for FE but I just don't like following that fast and that close. Occasionally I'll find something I can follow at 55-60 mph but not very often.

I've gotten used to driving slower on roads posted 65 mph. I find I'm able to drive 50-55 if that's what I want to do. I do have a big 'MPG' sticker on my back window so maybe that helps people understand why I'm not going 70.

My tires are labeled 44 psi but I have them at about 53. No, I'm not afraid of a blowout. Side topic: with a commute of 60 miles each way I carry a full size spare. If a tire does quit on me for whatever reason I want a fully capable one to complete my trip. I like donuts to eat, that's all.

Carpooling really improves fuel economy. Hurts your mpg just a bit but can double or triple your fuel economy!

Some other techniques I found on today's long 500-mile drive (check my gaslog for the big jump upwards)

When going downhill, do engine-on coasting. However, if going downhill over the speed limit, or there are sharp bends coming up, go back to drive, and try to get it to go into fuel-cut mode (done on my car be putting it in gear, accelerating slightly to engage lockup, then letting go (this only works when I have disconnected the lock-up control lead).

If you have lock-up that disengages at 80km/h (50mph), it may be that your most efficient speed is 51mph, but there is another efficiency peak when the torque convertor is slipping. On my car that was at about 35mph. So, I would do up-hill stretches at high-throttle load (just before enrichment), but once the car slowed down too much, I would go into neutral until about 35mph, then back into gear and would continue the up-hill at 35mph.

Finally, engine-on pulse-and-glide is great for mild downhill stretches where the car slows down but the 100-80km/h (62-50mph) stretch is prolonged by the slight downhill grade. (note you need to go into neutral when on the glide for this to work).

One more - Neutral at stoplights. Many people with automatics forget this one. Note my MPG % above EPA and you'll see it does help.

Use neutral as much as possable, stop-lights, down hills and prior to stops. Use the big gear. 28 city 35 highway 99 passat epa 21/31

Use neutral as much as possable, stop-lights, down hills and prior to stops. Use the big gear. 28 city 35 highway 99 passat epa 21/31

When you're not interested in reducing speed, neutral makes sense because it won't drag your speed down. When you want to reduce speed, use enough engine braking to trigger DFCO (if your car does DFCO).

It's commonly thought that higher RPM == more fuel usage, but does it if you're not stepping on the gas and the road is turning the engine (but, for whatever reason, not in DFCO)? Would the engine need to inject the same volume of fuel more often for more RPM, or it can it inject less fuel? Can anyone answer that definitively? I will when I eventually get a ScanGauge.

On my auto, idle is 750rpm, and fuel cutoff works above 2000rpm. Therefore, if I am driving with the engine at 1800rpm, it makes sense to pulse, and then glide in idle. Otherwise it injects lots of fuel even if it could have been in cut-off mode.

More modern cars have much better cut-off modes, however. Or at least they should! (The Toyota Avensis D4-D (diesel) has cutoff at any speed above idle :)

Wow, I must admit, some of this is hard to follow. Can anyone tell me what is the safest way to come out of neutral when I need to speed up?

What I have been doing is going into neutral up even the smallest road hills, then mildly accelerating downhill till I hit level or get done accelerating, then putting the car into neutral. My rpms are always at 9-1.1k when moving in neutral(750 idling).

So if I say... coast in neutral all the way over a hill, then mildly accelerate down, cut it to neutral then coast out till I am going about 5-10 mph less than the speed limit, should I rev my engine a little before putting my trans back into drive? I have recently started doing this, and it is the smoothest way to go back into drive while moving. Help?

I'm not sure about your Volvo, but in every GM I've ever owned (and probably some Fords I drove a lot) I never had to think about it, I just go from N to D without touching the gas pedal until D is fully engaged.

I run aftermarket rims and tires, have an auto tranny and a turbocharger. I do a couple things to help.

1. Reinstalled boost guage. I used to use it for performance, now I use it to stay in vacuum and make sure Im not in boost.

2. Feather the throttle to keep it under 2200rpms or so. I have "autostick" but I find if the RPMs get too high, I let off the throttle a little bit to get the transmission to shift then I speed up again. I only do this through the first 3 gears - 4th is OD for me and a weak point for the 41TE.

3. Speed up slowly, maintain speed limit or below. Duh

4. Try not to use either pedal. You shouldnt need to brake hard or speed up hard if youre in tune with traffic.

I do pretty well all things considering. We also have a 2008 Yaris that gets 40mpg with barely trying so thats the mpg car. Picked it up for 11k OTD with 1,400 barely used miles from a Chrysler dealership. Bare bones with 5 speed and the convenience package.

On my Odyssey, the transmission jolts a bit when going back into drive above about 40mph. In that case, I blip the throttle to about 2000 rpm to rev-match first. A little high seems to be smoother than a little low.

is it bad to turn off you car when your able to glide a good distance? because I do that. I have a 93 saturn sc2 auto. I have got several places on my usual routes that i can put my car into neutral, turn the car off and glide, you loose power steering, but 30+ you don't need it, and power brakes after a few hits. There is one area that i think i glide for nearly a quarter mile before the stop sign comes. i have to look at my tripmeter next time i go there. i only do this if i'm going to be coming to a complete stop, if something happens, suppose the light turns green before my spot, i just turn on the engine, wait for it to stablize and tap the accelerator to get the rpms up if need be, put it into drive and go.

g2k556, welcome to the site.

Check your car's manual for flat-towing ability. If it says you can tow it with all four wheels down then it's probably okay to EOC. If not then you are risking your transmission.

Good advice. I think those saturns are fine, though. I've seen them behind RV's.

yep, i just checked the owners manual and they are good for towing :thumbup:

One more thing. I tested this morning, and my Honda does fuel cut down to 1200 rpm.

Guys - I really like how this thread is continuing. I was afraid it would die on the vine when I made the original post since it seemed like very few people who cared about FE had auto trans vehicles.

I have to say that my continued work on driving style (and lately and more importantly driving route) has really increased my MPG even further. I hit 44 mpg this morning when I filled up. Not bad since the newly adjusted EPA estimate puts it at 28 or 29 combined. That's 52% above the gov't estimate. This is really important since I am trending towards putting 23,000 miles on my car this year with my daily commute, etc. (right now, 1894 miles a month).

I still don't have a ScanGauge but am developing a pretty good feel for what works and what doesn't. I am sure I am still missing out on some techniques that might bump me up another 1 or 2 mpg but can't convince myself to drop the $160 or so on a ScanGauge unit.

Thanks to everyone that has participated on this thread so far. A lot of you guys are a LOT more technically minded than I am and I haven't completely followed everything said but I am learning.

Thanks again!

Scott - all good stuff. That's about all I'm able to do in my Mustang, as with a carbureted car like my Mustang, there's no ScanGauge, no DFCO, and little if any benefit to neutral at stoplights. Indeed...I think neutral for me would be worse as the primaries are open to the same position, but in N it's revving 200rpm higher than in gear. I've inflated my tires to sidewall max (35psi) but won't go any further as they're pushing 14 years of age and one has a plug in it. Using the downhills to build momentum for uphills is an important one here, as we have a landscape dotted with rolling hills, and it usually helps to the tune of 5-7%.

So far, the biggest help to me has actually been installing a fan clutch (these cars didn't come stock with one unless it was a/c equipped, which mine is not), much more than even my right foot. Like the '68 hardtop I had in high school, the car has so much torque for its weight that your acceleratory style has little effect on the mileage - I've noticed less than 1mpg difference in both cars between my granny driving and harder driving. The fan clutch has a double whammy effect in that the car is able to run ~15* warmer and the motor isn't slinging a 5-bladed fan around at 1.8x engine speed everywhere I go. Informal observations about having my top up vs. down hasn't revealed the expected gain from having the top up, either.

jcp123,

I hear ya. Those older Mustangs were built well but not for mpg fuel efficiency. You could do a lot of things to make your Mustang get better gas mileage but then it wouldn't feel or drive like a Mustang any more. I think the best bet for you is to ride your 1100 motorcycle as much as possible. You could take it easy from a riding style with the bike and still get around 40 mpg or so. Plus, you would continue to get the surround sound sensory experience that can be only had with a bike or a convertable.

I know it is tough to find right now, but if you drive quite a bit, it might be worth trying to pick up a mid-90's subcompact import that can get better gas mileage and keep the 'stang and bike around for those enjoyable rides.

Hmm, I should update that sig. The bike's been gone for about 5 months now, but it was really easy on fuel - my commutes actually averaged around 47mpg, highway trips were pretty consistent at 52-53mpg! Fantastic for an 1100cc, but the dated design of the Shadows really comes through. Right now I'm saving up for a Harley Sportster to build a bobber bike out of as my fuelsaver - the big, heavy flywheel allows these torque monsters to cruise at low RPM's with bigger throttle inputs, reducing pumping losses and yielding pretty impressive mileage. My Dad and I are also working to get a '61 Mercedes 190b roadworthy for a family grocery getter. With a 1.9l SOHC four and a four-on-the-tree, it should be pretty decent in the mileage department.

After I'm done with school and move out, space permitting, I'd love to get a late '65 Mustang with the 200ci I6/3-speed stick combo - they're capable of touching 30mpg on the highway weighing in at only around ~2600lbs. The other option would be a '58 Chevy Biscayne 2-door post, Chevy's base model, with a 235 I6 and 3-speed overdrive. It's physically a large car, the same size as Chevy's Bel Air and Impalas, but weighs in at only about 3400lbs since it's a no-frills, radio-delete kinda car. Chevy's 235 is arguably a better-designed engine than Ford's 200, and with overdrive is able to push the extra 800lbs along at 30mpg as well.

The only problem with carb'd cars is that a lot of the little hidden tricks like DFCO and neutral at stoplights don't work on them. Other than that, they're capable of fine mileage, but automatics hold them way back, much more so than modern auto'd cars.

The other option would be a '58 Chevy Biscayne 2-door post, Chevy's base model, with a 235 I6 and 3-speed overdrive. It's physically a large car, the same size as Chevy's Bel Air and Impalas, but weighs in at only about 3400lbs since it's a no-frills, radio-delete kinda car.

1980 Buick Lesabre is 3400 lbs too, not quite as no-frills, and has a trunk big enough to park my VW in. Mine's got a 252 (4.1l) v6. I hope to eventually change it to fuel injection, but I think it's a bigger project than I originally anticipated. I originally thought I could throw a TBI, ECM, a few sensors, and maybe a fuel pump on it and it would work. I've come to realize that it seems I'll also need to change the gas tank and all the gas lines, and maybe some other stuff I've missed.

One more - Neutral at stoplights. Many people with automatics forget this one. Note my MPG % above EPA and you'll see it does help.

I've not really noticed a difference in RPM in Drive or neutral while at a stop light. I normally flux between 575 and 625 in both. In fact in neutral it takes longer to drop below the 600 line. Of course the car has always been an odd duck.

1989 Caddilac El

The engine has to do a little more work to push against the torque converter compared to if you're in netural. If you've got approximately the same RPM either way, then it's feeding a little more fuel in.

I've setup a fuel rate gauge (see the "realtime monitoring for pre-obd2 cars" thread), and the difference in my 2002 GMC is miniscule but definitely there.

On my Odyssey V6, it idles at about .05 gph in gear, and in neutral it flips back and forth between .04 and .05. The resolution is really rough with numbers that low, but at least it shows that neutral uses less fuel.

Noticed something today on Marvin, he has a 3 speed hydraulic torqueflite derived transaxle....

Below 2000 rpm, if I put it into neutral for a second or two, then put it back in drive it appears not to engage drive until I press the gas again... thus you can be "neutral coasting" while still having instant access to acceleration should you require it... it appears to stay out even when you brake to a stop, and only engage when you touch the gas again. It does seem however to go back into drive fully when over 2000 rpm, guess that's because the tranny can still push the engine. Seems to need a certain amount of push from either side to engage, and lacking that stays out.

However, I think I remember one time a while back, I shifted into N, then went back to D and coasted down to a stop without brake use... and it sat there 5-10 seconds and then engaged drive slowly and began to crawl again. I didn't make any connections then about it staying in N though.

P&G (using N but not EOC) definitely works in an automatic. Proof is in the latest gaslog entry for my truck. I haven't gotten this kind of mileage in years, since the truck was brand new and I was driving 100% highway with the cruise control at 65. 18.31mpg!!!

I've been pulsing at 2000 to 2500 rpm, using as much throttle as I can while staying in third or fourth gear. It may not be as good as if it was manual, but it's sure better than nothing.

I've noticed on my '05 Passat that if I use the cruise control going over hills that it holds a higher gear longer than if I try to drive it myself. I even tried putting it in tip-tronic mode to hold top gear but the computer makes it down shift. I have been having lots of fun with coasting in N on the downhills. It does not seem to be making a big difference in my FE though.:(


jcp123- A newer tranny with OD and lockup would probably give your Mustang great highway mileage.


Phil

Vag-Com may be able to adjust your transmission behavior. Check on vwvortex.com or a Passat forum.

I have a 99 passat. The triptronic holds 5th down to 30 mph, and I've had great success with pulse and coast in N Increased mpg from 20 to 26 mpg in city driving.

phlp100,

You might try gradual acceleration downhill and then coast in N going uphill. You just need to accelerate enough to get about 5 or so over the speed limit and then coast to about 10 under the speed limit if you can.

I have tried this with great success. It takes some experience to fine tune the driving style and when to accelerate and coast but is well worth it. If you had a ScanGuage, you would probably learn on this faster than I have (haven't been willing to shell out the money for a SGII yet).

You can look at my Gaslog chart and see the gradual improvements over the past few months with neutral coasting up hill. I am now seeing about 39 mpg when I started with only 32.

Good luck!

Scott, I'm curious why you chose pulsing downhill and gliding uphill. Is it because you can get a more useful pulse without causing a downshift?

In my truck I've been pulsing uphill and gliding downhill, just like I do in my manual transmission car. The theory is that the engine produces power more fuel-efficiently at higher loads, and that the wider throttle opening reduces pumping losses too. (Additionally, your speed is more steady, which helps with the difficulties of P&G.) However, with an automatic it's tough to achieve those advantages because it will downshift. My strategy has been working for me, but maybe I'll try yours too, to see if it works even better.

I actually picked this tip up from PaleMelanesian and an article that he had forwarded to me.

I am not as technically adept as you on the shifting details of my auto trans (I am just a marketing guy) but I think the basic concept is to accelerate downhill and use the advantage of gravity to help multiply my speed acceleration while using as little gas as possible to reach speed. Then I coast uphill in neutral with my engine idling at 700 - 800 RPM. The more I can avoid using the gas uphill, the better off my FE.

Now, I can't always coast all the way uphill in Neutral so I sometimes have to shift into drive and maintain my slowest speed through the rest of the slope (usually around 55 mph or so on the highway).

I am sure there is a lot more science behind this technique that I am not totally aware of. I will let PaleMelanesian weigh in on more details on this technique if he chooses too. All I can tell you is that I saw an immediate 2 mpg increase in my fuel efficiency when I shifted from coasting in Neutral downhill to this technique. I can't guarantee that it works equally well for all vehicles but it sure works for my 2000 Civic Coupe.

I forgot to mention that this technique mimicks that of a roller coaster where you are trying to build enough momentum going down hill to carry you through to the top of the next hill.

As with roller coasters, sometimes you don't have enough momentum to carry you through the top of a higher hill or steeper slope and you have to add some additional energy i.e. fuel to carry you through to the top of the peak.

Scott, I'm curious why you chose pulsing downhill and gliding uphill. Is it because you can get a more useful pulse without causing a downshift?

In my truck I've been pulsing uphill and gliding downhill, just like I do in my manual transmission car. The theory is that the engine produces power more fuel-efficiently at higher loads, and that the wider throttle opening reduces pumping losses too. (Additionally, your speed is more steady, which helps with the difficulties of P&G.) However, with an automatic it's tough to achieve those advantages because it will downshift. My strategy has been working for me, but maybe I'll try yours too, to see if it works even better.


holycow - not sure what your background is, but in HS physics you may have learned about vectors. When a block is on an incline, the weight vector has to be broken down so that one component is in the same direction as the incline.

So if you're going up a hill, this vector is working against you, requiring the engine to perform more work to maintain a particular speed.

If you're going down a hill, this vector is working with you, requiring the engine to perform less work to maintain the same speed.

Extend this a little further to P&G. If you are pulsing up a hill, you are asking the engine to perform even more work that it would normally do during a pulse on level ground. Regardless of the BSFC stuff we've been discussing, the bottom line is that more work now needs to be done by the engine (esp compared to level ground), requiring more fuel, thereby impacting FE.

On the downhill, you're getting some work for "free" from gravity. That same pulse on level ground will now get you a higher road speed, hopefully netting a better glide.

BSFC in an automatic...I'm not convinced yet. I'll say it again: it seems more about minimizing RPM and fuel flow rate, and less about hitting the BSFC.

Oh, no HS physics class is necessary to know that it takes more work to move a load uphill than downhill. However, regardless of when you pulse and when you glide, it still takes the same amount of energy to move the same weight over the same hills.

Pulsing downhill means a larger difference between your high and low speeds. Your high speed will be higher, and common knowledge is that waste from aerodynamic drag is not merely equal to the increase in speed but is exponential or some such. So, that, in addition to BSFC and pumping loss minimization (which in an automatic are difficult at best), are why I would assume that uphill pulse and downhill glide are the best.

Still, I can't argue with results, and Scott got results. Therefore I'll have to try it on my next tank.

Oh, no HS physics class is necessary to know that it takes more work to move a load uphill than downhill.

Sorry, wasn't trying to be a prick or anything, just never know about who knows what.

However, regardless of when you pulse and when you glide, it still takes the same amount of energy to move the same weight over the same hills.

Pulsing downhill means a larger difference between your high and low speeds. Your high speed will be higher, and common knowledge is that waste from aerodynamic drag is not merely equal to the increase in speed but is exponential or some such. So, that, in addition to BSFC and pumping loss minimization (which in an automatic are difficult at best), are why I would assume that uphill pulse and downhill glide are the best.

However increasing speed (say pulsing from 60 to 70 mph) when traveling uphill requires more energy than maintaining a constant speed uphill - correct? So why does it make sense to pulse uphill if the car has to expend more energy (i.e. use more fuel) to accelerate uphill?


Pulsing from 60 to 70 mph downhill would require less energy due to the conversion of potential to kinetic energy - correct?

Furthermore, the energy wasted to aerodynamic drag is going to be the same regardless of going uphill or downhill, right? So why not take advantage of the free work from gravity to offset the energy wasted to drag, rather than use more fuel on the uphill to work against both the incline and aero drag?

Sorry, wasn't trying to be a prick or anything, just never know about who knows what.

NP, I didn't think you were trying to be a prick.

However increasing speed (say pulsing from 60 to 70 mph) when traveling uphill requires more energy than maintaining a constant speed uphill - correct?

That's fine if you're only going up the hill, but as I said it takes the same amount of energy to move the vehicle through the same length of road whether you power up and coast down or power down and coast up. The same amount of work is being done; that's a basic and unalterable physics concept.

Pulsing from 60 to 70 mph downhill would require less energy due to the conversion of potential to kinetic energy - correct?

Yes, but you're going to gain the same amount of free work from gravity boost whether you're pulsing or gliding. In the meantime, you're going to lose the same amount of work going up the hill whether you're pulsing or gliding.

Furthermore, the energy wasted to aerodynamic drag is going to be the same regardless of going uphill or downhill, right?

Not in the strategy we're discussing. If your desired average speed is 60, and you have to do 75 downhill to maintain your average, that means you spend a lot of time doing 70 or 75 mph. If you pulse uphill and glide downhill, you can pretty much keep a steady 60mph. Since aerodynamic drag increases with the square of speed, it's unlikely that you make up for it when you get down to 50mph up the hill.

I can sit around and theorize all I want, applying knowledge that I don't entirely posess and just guessing at the math, but it doesn't change the results that Scott (and presumably you) get -- and no amount of knowledge beats experience, so I'll just have to try it.

The idea of pulsing uphill is exactly about using the best BSFC. If you aim for the peak point (usually around 2000 rpm and 3/4 throttle) on level ground, you'll be going waaaaay fast in a short time. So you pulse and glide. The engine puts out the needed energy efficiently, and then drops to idle level, which is nearly zero.

If you have hills, you can drive up the hill at high load and then coast down, while maintaining fairly even speed. You're still pulsing and gliding, but without the speed variation. As stated above, this does also help with aerodynamics. You're using the engine at its most efficient point and building up potential energy in the form of elevation. Then you can use it up on the way down for (nearly) free. It's the same as P&G on the flat only without the extreme speed variations.

I think the pulse-uphill style works better with manual transmission, honestly. However, I took a 600-mile highway trip last week in the Odyssey (rated 18/25 old epa) and used a mild pulse-uphill coast downhill style. 28.5 mpg fully loaded with 6 people and camping gear and AC.

I think the pulse-uphill style works better with manual transmission, honestly. However, I took a 600-mile highway trip last week in the Odyssey (rated 18/25 old epa) and used a mild pulse-uphill coast downhill style. 28.5 mpg fully loaded with 6 people and camping gear and AC.

Could be splitting hairs, yes.

On my recent drive to NY (400+ mi), the "hills" that worried my were the Catskill Mountains. Pulsing uphill didn't seem to make much sense, rather, maintaining constant rpm was what I was concentrating on. I would pulse near the top to get back up to 65 mph or so and then glide downhill. The big downhills made for very long glides that undoubtedly boosted mileage.

Not in the strategy we're discussing. If your desired average speed is 60, and you have to do 75 downhill to maintain your average, that means you spend a lot of time doing 70 or 75 mph. If you pulse uphill and glide downhill, you can pretty much keep a steady 60mph. Since aerodynamic drag increases with the square of speed, it's unlikely that you make up for it when you get down to 50mph up the hill.

Yes, I agree that it depends on the speed range you're trying to work within.

I can sit around and theorize all I want, applying knowledge that I don't entirely posess and just guessing at the math, but it doesn't change the results that Scott (and presumably you) get -- and no amount of knowledge beats experience, so I'll just have to try it.

As I indicated to Pale, we could be splitting hairs here.

Well, I filled up today and then attempted to try pulsing down and gliding up. Unfortunately, I won't be able to find out if it's more effective. It is not practical for me for two reasons:
- It can't be done if there's other traffic on the road, due to the buffer distance required
- I just don't have the patience even when there's not other traffic around

I did get over 1mpg improvement on my previous tank, doing nothing different than I did for that tank, and I can't confidently identify why. Take a look at my truck's gaslog...

jcp123- A newer tranny with OD and lockup would probably give your Mustang great highway mileage.



I don't doubt it. 2500rpm @ 60mph isn't a recipe for huge MPG. Maybe someday...getting the crossmembers and other hardware along with a shortened driveshaft is a bit much to contemplate at the moment...especially when the trans I have now only has 4800 miles on it.

2500 @ 60 isn't too terrible, methinks there are issues with efficiency below 1500 and over 3000.

Well I can't say how well I can P&G, as the mountains here make it difficult, and I drive mostly (95%) in town. But I have noticed that by staying under 2000rpms, neutral coasting (this car rocks at that, so heavy), and "pulsing" to a reasonable speed when needed, I've managed to get 200 miles so far on a half tank (I know my gauge, half is more like 1/8 under half). I can't wait to finish the tank off, and see what kind of mileage I've managed. 21.4mpg was the last best in town, so far I'm on track for at least 24mpg, maybe more.

I'll say its challenging to keep the rpms under 2000. I have to contantly watch them and listen, and adjust when it shifts gears. I do know if I can reach 38mph with a warm tranny I'll hit lockup, and that drops me to 1100rpms. That's the sweet spot for crossing town. :) Helps bundles too that Bozeman is slopped, I can pretty much coast to work every night.

Now if it'd only stop raining I'd bike instead.....

2500 @ 60 isn't too terrible, methinks there are issues with efficiency below 1500 and over 3000.

Hmm. Below 1500...that's where this car lives a lot of the time...

I let off the throttle a little bit to get the transmission to shift then I speed up again.

This seems to be a good technique to perfect for auto transmissions.

Hmm. Below 1500...that's where this car lives a lot of the time...

Which one? Isn't so bad on a manual, any autos that don't lockup below 2000 rpm it's bad though. I can get into lockup at 1500 in my escort though. Have to be going about 40 IIRC, but can ease it down to about 33ish and it will stay in.

Which one? Isn't so bad on a manual, any autos that don't lockup below 2000 rpm it's bad though. I can get into lockup at 1500 in my escort though. Have to be going about 40 IIRC, but can ease it down to about 33ish and it will stay in.
Dang, 33 in lockup is good. I hit lockup about 39-41mph, but it drops to 1100rpm, soo not much room to improve. I can hold it in 4th at 30mph around 1200rpms though, unlocked. Its the accelerating that kills my FE. That V6 just sucks gas when accelerating the car's mass. And accelling below 2000rpms makes me as slow as me biking (roadbike ftw).

Eh. It redeems itself with 34mpg on the highway.

Went to pick up a friend today and took the 94 intrepid. The good thing was it has a gauge that goes up to 99mpg on the read out. I use the Intrepid for practice technique and it is a automatic with overdrive. I notice in drive that the shift pattern is not the best for FE. I tried starting in first, quickly into 3rd, then into drive. When i did this i noticed it went into overdrive sooner and it held at 1300 to 1400 rpm. At 40 mph it was showing 56 mpg for a bit then 44 mpg. I will play around with this to see just how much i can squeeze out of it. It has 168k on the clock. I don't drive it all that much and was thinking about getting rid of it. My daughter was driving it to school and back and was showing 16mpg avg. I got it up to 28 mpg.

My parents have an '07 Ford Explorer Eddie Bauer 4x2 V6 with Towing Package. The reason I mention the Towing Package is because it changes the Axle Ratio from 3.55 (standard) to 3.73. The purpose is to provide a little extra pull from a stop to help get the weight of both the SUV and the weight it's towing in motion. To the best of my knowledge, a changed axle or possibly gear ratios are often part of similar Towing or Heavy-Duty packages that many mid- and full-size SUVs may have.

When it's not towing anything, my parents will never tow with this vehicle, the benefit is that it feels a little snappier off the line. The negative- a bit more fuel consumption.

My mom drives this vehicle 90% of the time and she has never managed to break 16MPG average. Miraculously, I can coax 19+MPG out of it when I drive it for a while.

I finally rode along with her a few days ago and observed her driving- she always seemed to be lightly coasting or very lightly acclerating. A while on the accelerator, then a while off of it....I found the culprit! I also took her on a 10-mile stint on the expressway with her driving in one direction (16.6mpg) at approx. 70mph and then I drove the 10-miles back with the cruise control set at 70mph. I topped 20mpg, but just by a hair- 20.1mpg.

It was an eye opener for both of us...and I can't believe I'd never noticed her erratic accelerator foot before (I needed a Dramamine after a few miles)...then again, I avoid being her passenger whenever possible. =)

Seems to me all that coasting could put a strain on your automatic transmission fluid because of decreased cooling caused by low fluid circulation.

It may actually help your MPG because it works better, but I do know that Amsoil ATF will stand up to the heat better than any other fluid.