Lowering your car in order to increase fuel economy

[Matt Timion]

Recently a few members of this forum have lowered their cars and have found an increase of fuel economy. krousdb noticed a 3 mpg impovement instantly.

Lowering your car will theoretically improve your gas mileage as it reduces frontal area of the car, lets less air under the car, and as a result increases the aerodynamic "flow" of your entire ride.

This thread will be a place to log results of this particular modification. Please give Fuel economy before and after. Please log as many tanks as possible for both the before and after condition.

[krousdb]

Originally Posted by Matt Timion

Recently a few members of this forum have lowered their cars and have found an increase of fuel economy. krousdb noticed a 3 mpg impovement instantly.

Yes but that is just one data point, new data that I was able to match with old data under very similar environmental conditions.

Since temperature has a significant impact on FE, and since my old data only contains results at temps between 18F and 30F on the AM trip and between 30F and 41F on the PM trip, as the days get warmer, I will have less likleyhood of finding matching old data for comparison. Hopefully, with a few more matches, I can be able to quantify the FE improvement with more certainty.

[Matt Timion]

Originally Posted by krousdb

Yes but that is just one data point, new data that I was able to match with old data under very similar environmental conditions.

Since temperature has a significant impact on FE, and since my old data only contains results at temps between 18F and 30F on the AM trip and between 30F and 41F on the PM trip, as the days get warmer, I will have less likleyhood of finding matching old data for comparison. Hopefully, with a few more matches, I can be able to quantify the FE improvement with more certainty.

now that you have the SuperMID, I do believe that individual trip MPGs will be sufficient for this type of experiment. If anything it will show that there is an increase in FE.

[krousdb]

Originally Posted by Matt Timion

now that you have the SuperMID, I do believe that individual trip MPGs will be sufficient for this type of experiment. If anything it will show that there is an increase in FE.

True, but will that be due to better aerodynamics or to higher temps?

[Matt Timion]

Originally Posted by krousdb

True, but will that be due to better aerodynamics or to higher temps?

I guess this is one reason to get adjustable coilovers, eh?

I guess as long as keep your temps consistent (as you compared this run to another run with similar temps) it shouldn't be much of a problem.

Maybe I'll install adjustable coilovers on my car this year in order to test this very thing. Lower it for highway trips.

[MetroMPG]

i don't have a hard time believing that krousdb's drop would net a 3mpg gain at highway speeds. don't forget it has also let him change his driving style slightly (less momentum lost in cornering), which also helps in lower speed driving where the aero effect is negligible.

one way i was thinking of testing this on a car with non-adjustable coils.... jack up each wheel from the suspension point (not the body/frame) so the spring compresses, and wrap nylon webbing or strong rope multiple times around the compressed coils. if the straps hold when you lower the jack, then you can do a relatively easy before & after run. just cut the strap for the "after" run.

makes it a little tough to do a proper a-b-a test though, since i imagine it will take 5-15 minutes to strap each spring (during which time the car cools down, weather/wind conditions change, etc, etc.).

and maybe it won't work at all (straps holding). i have no idea. but i was thinking of trying it.

i suppose you could try it with coil compressors too.

[MetroMPG]

Lower it for highway trips.

i think there was a lincoln that did this - one of the "mark xxx" 2-door coupes. yup, here it is:



1997 Lincoln MarkVIII LSC
(from http://www.dftowel.com/lscsale/index.html)

And most interesting of all this car's great innovations and features is it's ability to lower itself at highway speeds. At about 50mph the car lowers itself to the ground for better aerodynamics, performance, and fuel mileage. The Mark VIII was featured in a TV commercial demonstrating it's ability to lower itself at highway speeds. You can see this ad by clicking here.

[SVOboy]

What the heck, that's insane! I wonder what kind of improvement their chalking that up to, though, ugly thing.

My camber kit shipped out today so as soon as I get that I will be dropping 3 inches or so, doing a camber kit diy, and an alignment diy, and we'll see how well that helps,

[krousdb]

Originally Posted by Matt Timion

Recently a few members of this forum have lowered their cars and have found an increase of fuel economy. krousdb noticed a 3 mpg impovement instantly.

Lowering your car will theoretically improve your gas mileage as it reduces frontal area of the car, lets less air under the car, and as a result increases the aerodynamic "flow" of your entire ride.

This thread will be a place to log results of this particular modification. Please give Fuel economy before and after. Please log as many tanks as possible for both the before and after condition.

Just a follow up on the return trip....

The trip back was 50.90, just short of my best return trip of 51.39. I did have a bit of a traffic jam that hurt. Without it I would have equalled the 51.39 at least. But certainly not 3 MPG higher like the morning trip. So far it looks like the lowering helps the morning trip, but not the evening trip. That doesn't make sense. More data points to come.

On a related note, the SuperMID says this tank is at 370 miles, 51.4 MPG. The digital fuel gauge shows 54.0 MPG. Perhaps I over compensated for the SuperMID over registration. Perhaps another tweak is in order after my next fill. I hope so anyway.

[krousdb]

- 3/7/06 Morning Commute: 21F, Dry roads, 10 MPH tail wind, engine on 72% of distance, 55.22 MPG

- Closest matching pre drop data:
2/27/60 Morning Commute, 18F, Dry roads, 10 MPH tail wind, engine on 72% of distance, 52.28 MPG

- Current Tank FE as measured by SuperMID
395 miles, 51.61 MPG

[philmcneal]

out of context i noticed you use mobil 0-20 for your transmission fluid. Is that the same as your engine oil, or different lubricant?

[krousdb]

Originally Posted by philmcneal

out of context i noticed you use mobil 0-20 for your transmission fluid. Is that the same as your engine oil, or different lubricant?

It is the same for both engine and transmission.

[krousdb]

- 3/7/06 Evening Commute: 39F, Dry roads, 10 MPH head wind, engine on 78% of distance, 52.48 MPG

- Closest matching pre drop data:
3/1/06 Evening Commute, 41F, Dry roads, 10 MPH head wind, engine on 81% of distance, 51.39 MPG

- Current Tank FE as measured by SuperMID
421 miles, 51.66 MPG

[SVOboy]

Woot woot. That's pretty nice, m8. I got my front camber kit today so I'll be trying to drop 3" or so pretty soon, when I get my car running, . Junkyard tomorrow though.

[krousdb]

This trip started OK but I began to get concerned when I was dropping below my target FE at the various milestones on my route. I was downright pissed when my IGN off coasts were ending way too early. I almost pulled over to check if I had a low tire. But when I got to work I checked weather.com and found that my normal 9MPH tailwind had turned into a 6MPH headwind today. Not bad results considering a net 15MPH increase in wind speed.

- 3/8/06 Morning Commute: 26F, Dry roads, 6 MPH head wind, engine on 70% of distance, 54.29 MPG

- Closest matching pre drop data:
3/1/06 Morning Commute, 28F, Dry roads, 9 MPH tail wind, engine on 69% of distance, 55.00 MPG

- Current Tank FE as measured by SuperMID
447 miles, 51.80 MPG

[Matt Timion]

It's amazing to me how much you use wind to your advantage. Wind is never that consistent here, or if it is I never notice it.

[krousdb]

Originally Posted by Matt Timion

It's amazing to me how much you use wind to your advantage. Wind is never that consistent here, or if it is I never notice it.

During the winter here the prevailing winds are usually from the North. So most of my drive to work has a tailwind but its payback time on the evening commute. That is part of the reason why my FE differs on each leg. Other reasons are more traffic on the evening drive and +200 ft elevation difference.

Also be aware that when I say tailwind/headwind, that doesn't mean a perfect tailwind/headwind. It means that the wind usually at my back/front as my route changes direction several times. As the crow flies I drive SSW in the morning and NNW in the evening.

During the spring, summer and fall, the winds are more variable in direction and speed.

[MetroMPG]

Originally Posted by Matt Timion

It's amazing to me how much you use wind to your advantage. Wind is never that consistent here, or if it is I never notice it.

i suspect you may not notice it. it doesn't take much to have an impact.

also it's harder to "see" wind in the winter when the leaves are off the trees.

i did a drive a week or so ago and i was seeing 57-58 mpg at 80 km/h. i also couldn't see any wind. however when i headed back in the other direction it was obvious there was wind out there.

i tend to be very aware of wind anyway, since i sail a lot.

[krousdb]

Originally Posted by Matt Timion

It's amazing to me how much you use wind to your advantage. Wind is never that consistent here, or if it is I never notice it.

I have spent a considerable amount of time trying to adjust my route such that I have a tailwind on the way to work and on the way back. So far I have had only limited success. :-)

[krousdb]

- 3/8/06 Evening Commute: 41F, Dry roads, 9 MPH TAIL wind, engine on 80% of distance, 54.20 MPG, A NEW RECORD FOR THE EVENING COMMUTE thanks to the tail wind.

- Closest matching pre drop data:
3/1/06 Evening Commute, 41F, Dry roads, 9 MPH HEAD wind, engine on 81% of distance, 51.39 MPG

It appears that having a 9 mph tail wind versus a 9 moh headwind is worth nearly 3MPG.

- Current Tank FE as measured by SuperMID
473 miles, 51.93 MPG

- 54.5 MPG as measured by the digital fuel gauge.

[SVOboy]

Just fill up your damn tank and see if the MID or the fuel gauge is wrong!!!

On another note, I saw you say somewhere else that the del sol hasn't gotten the mileage you want. For serious?

[MetroMPG]

Just fill up your damn tank and see if the MID or the fuel gauge is wrong!!!

i see i'm not the only one interested in krousdb's daily reports

they make me want to go out and drive around - for no other reason than to see what kind of FE numbers i can get! it almost makes me wish i had to commute to work...

[krousdb]

Originally Posted by SVOboy

Just fill up your damn tank and see if the MID or the fuel gauge is wrong!!!

On another note, I saw you say somewhere else that the del sol hasn't gotten the mileage you want. For serious?

What I said was that I was looking for a CRX HF or a Civic VX. The del sol is heavy and not built for FE like the others. i am very happy with what I am getting from the del slow but I coulda done much better with an HF or VX. Thats why I plan on the CX tranny swap and possibly the vtec-e swap. That way I get to have my sporty 2 seater with removeable top and awesome FE. For me, awesome FE is 70. But then again, I have been spoiled by the Prius. :-)

[SVOboy]

Ah, sorry, I was confused by what you had written. Another reason to get my car running is to pick up that tranny now that I'm on spring break.

[krousdb]

Originally Posted by SVOboy

Just fill up your damn tank and see if the MID or the fuel gauge is wrong!!!

Patience young man, patience. The longer the test, the more accurate the results.

[krousdb]

Foiled by the headwind and wet roads. The warmer temps this morning appear to have been mostly negated by the wet roads when compared to yesterdays results. Tonight will be even warmer, 59F and I will have a 13MPH tailwind. Unfortunately there will be rain and that +200ft elevation change. :-(

- 3/9/06 Morning Commute: 44F, WET roads, 5 MPH head wind, engine on 67% of distance, 55.59 MPG

- Closest matching pre drop data:
No matching data. Temps too warm, winds reversed.

- Closest matching post drop data:
3/8/06 Morning Commute, 28F, Dry roads, 6 MPH head wind, engine on 70% of distance, 54.29 MPG

- Current Tank FE as measured by SuperMID
498 miles, 52.10 MPG

[krousdb]

WOOT!! Warm weather is here! At least for today. Even the rain held off and the tailwinds kicked up for my evening commute.:-)

- 3/9/06 Evening Commute: 64F, DRY roads, 13 MPH TAIL wind, engine on 80% of distance, 56.95 MPG. :-) :-)

- Closest matching pre drop data:
No matching data. Temps too warm, winds reversed.

- Closest matching post drop data:
3/8/06 Evening Commute, 41F, Dry roads, 9 MPH TAIL wind, engine on 80% of distance, 54.20 MPG

So it would appear that the 23F temp delta, and to a smaller degree a 4MPH heartier tailwind was worth 2.75 MPG or about 5%.

- Current Tank FE as measured by SuperMID
524 miles, 52.33 MPG, or 55.1 MPG as measured by the Digital Fuel Gauge.

It is beginning to look like I overdid it on the SuperMID calibration. If the digital fuel gauge is indeed correct, I will need to increase the SuperMID fuel parameter by 5.25% and likewise add 5.25% to my trip data FE. If so, today's evening FE would be 59.94 MPG. And the 3/6/06 morning commute of 58.36 would be bumped up to 61.43MPG. My current tank would then be 55.1 MPG, equivelant to the combined EPA estimate for the 2004-2006 Prius.


W000000t!!!

Ahem.... I think I should wait until I fill the tank before I celebrate. Hmmmm. Maybe tomorrow. :-)

[krousdb]

Originally Posted by krousdb

More headwinds and wet roads this morning, but warmer still.

- 3/10/06 Morning Commute: 53F, WET roads, 16 MPH head wind, engine on 69% of distance, 56.04 MPG

- Closest matching pre drop data:
No matching data. Temps too warm, winds reversed.

- Closest matching post drop data:
3/9/06 Morning Commute, 44F, WET roads, 5 MPH head wind, engine on 67% of distance, 55.59 MPG

- Current Tank FE as measured by SuperMID
549 miles, 52.48 MPG

[SVOboy]

Doing pretty good, d00d. It was that cold out in pittsburg today?

[krousdb]

Originally Posted by SVOboy

Doing pretty good, d00d. It was that cold out in pittsburg today?

Yep, 53F, I noticed that it is warmer in your area.

I will fill tomorrow. At that point I will mafe the final calibration on the SuperMID.