Place your bets on the smart...

[smartzuuk]

I'm aiming for at least 100 mpg US based on repeatable round trips of at least 100 miles.

Here's the plan for the smart, as I see it today:

Current (stock) front tire width is 145mm, rear is 175mm

I've got some steel wheels in trade now, and will be putting the fronts from this set onto the rear.

In Europe, the car is rated for 3.1 L/100 hwy with the 145/175 combo - but with a wider combo (175/195) it is rated at 3.3

So there is roughly a 6.5% penalty based on the extra 50mm per side of the car. My best guess is that I can gain 4% economy by putting the narrower tires onto the rear. (Note: 2000-2002 smart diesel models came with 3.5 inch front wheels instead of 4 inch, and had 135 mm tires as stock... I could acquire those, but not at 'any cost'...)

I'm going to do a wheel skirt mod. Not going to get technical on this one - simply put, I'm going to use Darin's number of 3% as a gain.

Vortex Generators - this one could be interesting. The smart is .36 cd I think, and it's abrupt end at the back seemingly make it a good candidate for the VG mod. I'm going out on a limb and saying another 2% gain there.

These mods collectively add up to a 9% potential improvement. Being that I can already get 93 mpg US on a round trip in cold weather (39-45F) without my Milligan's fuel conditioner - getting repeatable round trips of 100 mpg is very realistic. The question remains at what speed... I'll aim to do it at 50 mph.

I don't need to pulse, glide, or go fishing to do any of this... I'll simply set the cruise and go...

There are a host of other things to play with, but they are all small percentage items IMO.

Thoughts?

I do plan on keeping good records of these mods, and posting the results.

[Matt Timion]

First, good luck!

I'm surprised that the CD of the SMart is so high. Car engineers continue to amaze me when they build "high MPG" cars with horrible drag coefficients.

As for the speed, I think the scangauage is the best critic. Find the "sweet spot" and let it rip.

I have a road trip planned for California in a month. 1 1/2 years ago the same road trip yielded 46 MPG in my 89 Civic LX. I'm hoping to break 50 mpg in my Fit. I plan on going 65MPH the entire way, travel time be damned.

Unless, of course, I get better MPG at 70mph.

[zpiloto]

I'm aiming for at least 100 mpg US based on repeatable round trips of at least 100 miles.

These mods collectively add up to a 9% potential improvement. Being that I can already get 93 mpg US on a round trip in cold weather (39-45F) without my Milligan's fuel conditioner - getting repeatable round trips of 100 mpg is very realistic. The question remains at what speed... I'll aim to do it at 50 mph.

I don't need to pulse, glide, or go fishing to do any of this... I'll simply set the cruise and go...

There are a host of other things to play with, but they are all small percentage items IMO.

Thoughts?

I do plan on keeping good records of these mods, and posting the results.

Good luck. I think the slower the better if traffic will allow. There's a sweet spot as far as MPH go just need to find it with your gearing and the SG. With the cd of .36 I think some where around 40 MPH would smash it.:thumbup:

[smartzuuk]

Well, 40 mph netted the 93 mpg to which I refer... so that is a likely place to start. Thanks!

[MetroMPG]

The only potential fly in the ointment: at 40 mph, the savings from the aero mods listed will be smaller than estimated. e.g. The 3% improvement I measured from wheel skirts was taken @ 95 km/h / 59 mph.

I'm not saying don't do the aero mods. Just that they won't contribute as much if you drive slower than the test speed.

Still, I won't be surprised if you pull it off. :)

EDIT: also, you should get better fuel economy if you don't use cruise control, and instead allow the vehicle speed to rise/fall with the grade.

[smartzuuk]

The beauty of the smart is that, when coasting in gear, it doesn't use fuel... I'll have to dig up the technical explanation...

...the same is true with cruise downhill - it may still stay 'engaged' (ie: ready to pick it up at the bottom), but the car may not use any fuel if the grade is sufficient... the car will speed up as well, if it's REALLY sufficient...

The drive by wire system in the smart loves cruise - yes, I can get get great mileage manually too... so I will try tests with and without cruise...

I am hoping to do this at 50 mph - so hopefully my wheels skirts will offer similar results. (I have achieved 105 mpg on a non-round trip going 50 mph).

[MetroMPG]

Does the smart transmission truly "freewheel" when you lift off the accelerator? I understand diesels don't engine brake much.

And do you happen to know any smarties around Brockville, ON who would be willing to show me his/her smart? I'd like to see one up close sometime. (Or get a ride, or better yet drive one. :) )

[smartzuuk]

I'm working on getting you matched up with a smart owner.

There were some discussions about the fuel cutoff here (http://www.clubsmartcar.ca/forums/viewtopic.php?p=14147&highlight=cutoff#14147). And somewhere else as well, but finding the thread at CsC is a tricky thing... I need to review further to collect up the pieces of discussion...

[CO ZX2]

I'm aiming for at least 100 mpg US based on repeatable round trips of at least 100 miles.

Here's the plan for the smart, as I see it today:

Current (stock) front tire width is 145mm, rear is 175mm

I've got some steel wheels in trade now, and will be putting the fronts from this set onto the rear.

In Europe, the car is rated for 3.1 L/100 hwy with the 145/175 combo - but with a wider combo (175/195) it is rated at 3.3

So there is roughly a 6.5% penalty based on the extra 50mm per side of the car. My best guess is that I can gain 4% economy by putting the narrower tires onto the rear. (Note: 2000-2002 smart diesel models came with 3.5 inch front wheels instead of 4 inch, and had 135 mm tires as stock... I could acquire those, but not at 'any cost'...)

I'm going to do a wheel skirt mod. Not going to get technical on this one - simply put, I'm going to use Darin's number of 3% as a gain.

Vortex Generators - this one could be interesting. The smart is .36 cd I think, and it's abrupt end at the back seemingly make it a good candidate for the VG mod. I'm going out on a limb and saying another 2% gain there.

These mods collectively add up to a 9% potential improvement. Being that I can already get 93 mpg US on a round trip in cold weather (39-45F) without my Milligan's fuel conditioner - getting repeatable round trips of 100 mpg is very realistic. The question remains at what speed... I'll aim to do it at 50 mph.

I don't need to pulse, glide, or go fishing to do any of this... I'll simply set the cruise and go...

There are a host of other things to play with, but they are all small percentage items IMO.

Thoughts?

I do plan on keeping good records of these mods, and posting the results.
Right on!! I admire your enthusiasm. Start driving.

In the words of the great Nascar legend, Dale Earnhardt:
"Don't tell me what you're going to do, show me what you've done".

Best of luck, COZX2

P.S. What diameter and bolt pattern are your wheels?

[smartzuuk]

In the words of the great Nascar legend, Dale Earnhardt:
"Don't tell me what you're going to do, show me what you've done".

P.S. What diameter and bolt pattern are your wheels?

93+ mpg US during 100 mile round trip thus far, as per pen and paper... I've done between 94 and 105 on one way trips...

As much as I trust the Scanguage numbers within a certain range, there are some *glitches*, and I have already seen them...

The wheels are a three-bolt pattern, and you're lucky to get tires here for stock size... but seeing as 800,000 of these exist in Europe, there's lots there.

[zpiloto]

What's the route like? If it's highway pick a time when there is enough traffic to provide a vacuum to pull you along but not enough that it's stop and go. Get in the slow lane and let them pull you along. I agree with Metro on the CC, manual control with load is the way to go. Also don't begin the quest with a cold engine. Does the smart have a under tray? If not add that to the list.

[smartzuuk]

Back to the 'freewheeling'...

For curiousity sake, I dropped the car into N several times yesterday... immediately, fuel usage goes to between .2 and .6 L/100km, as opposed to just leaving it in gear, which displays 0.0

[omgwtfbyobbq]

What's the difference in energy lost between engine in gear and engine in N? Does the additional distance traveled at some average speed make up for the engine idling?

[smartzuuk]

I understand what you are saying (I think) - meaning, if going downhill, would you travel far enough at .6 L/100 km (idling, out of gear) to outweight the benefit of going not as far at 0.0 (coasting in gear)?

No practical way for me to test this. My proposed 101 mile route doesn't have drastic elevation changes (range is 20 to 135 feet)

In city driving... I accumulate a double bonus for coasting in gear up to lights, slower traffic etc... a) less fuel consumed by easing off the accerator sooner obviously and b) even less fuel consumed by coasting longer, and not arriving at a point where I would have to actually idle

So yes, there is technique in how I drive. I'm not autopilot! Even the cruise which I use heavily is constantly adjusted, as every press of the button is 1 km, which is a total bonus.

The bottom line is that with no throttle applied, as long as you are moving, the car uses no fuel, so I am milking that for all it is worth. This is why I say no P&G/fishing in my application... although, I guess in a way, I am P&G, just not the same way as others.

[MetroMPG]

I'm working on getting you matched up with a smart owner.

Cool, thanks.

--

Ah, so you CAN go into neutral from any gear! I thought that being a sequential shifter, it would be like my last motorcycle where to get to neutral from 6th, for example, I had to shift sequentially down through 5-4-3-2 to get to N. (Although the motorcycle had a clutch, where the smart doesn't).

As for what's better, decelerating in gear with engine braking & fuel cutoff, vs. freewheeling in neutral with the engine idling, sounds like a test or 2 is needed...

Like: reset the SG passing a marker at a fixed constant speed, drive past a second marker and go to neutral. Coast to a stop & record FE info as well as the point at which you stopped.

For the comparison run with engine braking/fuel cut-off, you'd have to practice to figure it out, but with trial & error you could work backwards and calculate the point from the "stop" mark at which you have to release the accelerator to engine-brake in fuel cut-off mode to come to a stop at the same point. Sorry if that's confusing!

The point would be to compare the 2 techniques covering the same distance and using the same initial speed.

Sounds like someone at the smart forum already figured out that when descending a grade, anything less than 7% will yield better FE if you go to neutral due to the engine-braking effect. That suggests coasting in N on level ground will also beat using fuel cut-off mode.

[omgwtfbyobbq]

I don't think you need to have changes in elevation over considerable distances, just find a marked route on google earth with a decent elevation change and run a couple SG segments. you can also measure the time it takes you to go whatever distance, and your initial and final speed. The difference in KE during both types of run should show you about how much drag is associated with the transmission, while your SG should show you which type of driving is more fuel efficient.

[psyshack]

I saw my first smart several weeks ago here in Tulsa on the broken arrow express way. It was Blue and Silver. I honked at the driver and give the thumbs up. He didnt seemed impressed that anybody knew what he was driving or how rare it is in these parts.

I bet you will get 100 mpg+ out of it before its all said and done.

I myself would buy a Atom over a Smart. :)

[smartzuuk]

Ah, so you CAN go into neutral from any gear! I thought that being a sequential shifter, it would be like my last motorcycle where to get to neutral from 6th, for example, I had to shift sequentially down through 5-4-3-2 to get to N. (Although the motorcycle had a clutch, where the smart doesn't).



Yes - you can go to neutral, and also - you can go back into gear.

The smart does have a 'clutch', vis a vis, a friction disc... but the control is electronic, rather than a pedal.

I'll have to look for somewhere to try using neutral for FE tests.

[MetroMPG]

Right you are. I should have said "clutch pedal" or "manual clutch".

Now, if one reason for not stopping the engine (e.g. P&G) is to keep oil flowing to keep the turbo from getting too hot (is that correct?), is an electric oil pump an option? I read that idea somewhere recently.

[smartzuuk]

A thought I guess, but that would require 'hybrid mode' on SG right? And I use 'diesela'.

Baby steps... LOL

[smartzuuk]

Haven't been around for a bit... but I also haven't forgotten. Just that December and january have been pretty cold and snowy months in Vancouver, BC... thus fuel economy isn't anything to aim for the stars with. I've been running snow tires at a paltry 28 PSI!

None-the-less... we managed to sell close to FIFTY scangauges to Canadian smart car owners... I have a couple left if anyone in Canada needs one. (SG II - new in box!)

I'll be updating my FE numbers soon. And you should see me drop several mpg at least.

[MetroMPG]

50 units? That's amazing! I bet you're a popular guy around the smart forum now.

[Peakster]

I'm surprised that the CD of the SMart is so high. Car engineers continue to amaze me when they build "high MPG" cars with horrible drag coefficients.


Isn't it really difficult to have good Cd with a short car? Long sedans can have nice gradual airflow over the car whereas air has to hit the front and trail off the rear of a short car much more abruptly. I'd be surprised to find any micro-car with a Cd of less than 0.32 or so without having the roof-line super low.

[Lug_Nut]

As for what's better, decelerating in gear with engine braking & fuel cutoff, vs. freewheeling in neutral with the engine idling, sounds like a test or 2 is needed...Deceleration in a high gear (at least down to the road speed/rpm at which the 'throttle'-by wire takes over for idle speed control) uses zero fuel and provides less engine brake effect than in a lower transmission gear.
The 'no fuel / less glide' or 'some fuel / longer glide' debate can be decided by determining if brake use is needed to limit speed gain.
If the brakes have to be applied to avoid exceeding a personal comfort level or speed, then use engine braking and zero fuel.
If the slope isn't steep enough to exceed this speed, then glide in neutral. The fuel at idle in neutral will be less than the amount of fuel necessary to prevent slowing while in gear.
To really maximize distance per fuel stop the engine (zero fuel use) and glide in neutral.
And remember that it is possible to coast down many hills at slow speed that require fuel to drive down at high speed.

[red91sit]

So, any updates on the 100 mpg goal?

[smartzuuk]

So..... Antoine as he is known here has managed a fairly lengthy 100+ mpUSg experiment this year... and possibly better, although I don't see much of a post about it anywhere.

I ended up loaning my smart car to a friend for 4 months (March to June). This pretty much ended thoughts of doing anything elaborate for experiments this year.

I've since sold this car and acquired a brand new one - a 2006 smart cabriolet cdi without air conditioning.

visit http://www.100mpg.ca to read more on that...

Anyhow, uh, I am planning on some mods to this car to carry on where I left off with the other. I achieved 2.8 L/100 km today on a trip to work. With the car more broke in now, it is possible to get really good numbers...

Oh, and the Scangauges sold like hotcakes this year. I think we have sold about 100 in Canada, mostly to smart owners..... I still get orders through my site.

Not mcuh new to report other than that. I don't have a gaslog up yet for the new car, but will probably start November 1.

[SVOboy]

Somewhere around there is a post about antoine's 100+ mpg fill, dunno where it is off the top of my head though.

Welcome back, :thumbup:

[smartzuuk]

He did two - I know the detail about the first 1000+ km tank which was 105 mpg.

But I see his gaslog entry shows another at 108 mpg, which I cannot locate details on. I will e-mail him. I presume a couple aero mods were employed.

So, I have my work cut out - I have achieved 105 mpg in a short trip, but need to plan a longer 1000+ km trip where I can regain the record.