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