mdadgar

Yeah, the problem is that ALL of our gas is 6%. No choice in the matter - that's all you can get!

- Mark

blittle

....and the congressional lobby in DC wants to push it to 15%!!!

mdadgar

Vote early, vote often.

- Mark

alx

this will destroy a lot of cars' fuel systems

Benzo 003

Mythbusters did this one.....2 identical cars on a closed oval racetrack with 5 gals each cruise set on 55.

non A/C car went several miles further.

mdadgar

Assuming 20 mpg, that's about a 2% difference (and an even lower difference above 20 mpg). Well into the car-to-car variability.

I'd say no meaningful difference with modern A/C systems.

- Mark

alx

I'd say yours is wishful thinking. But dont take my word for it. On a long trip on a flat section of the road set cruise to say 70, reset mpg and drive for a few miles. Then switch ac to the other state, reset mpg and drive. On my truck the difference is 28mpg vs 24mpg with the windows up. This is a repeatable result.

I can also tell most of the time when the ac compressor engages and disengages as the power goes down noticeably.

mdadgar

I'm just going by the data that was posted above.

In reality, I agree with you. Running the compressor ain't free.

- Mark

Popo

In my experience over the years with different cars, it makes no difference in the GL450 and my C55 AMG the way my wife or i drive, while when i used to drive smaller displacement 4 and 6 bangers it did make more of a difference.

The weather conditions (wind), driving style and fuel grades used make a much bigger difference in this size vehicle as does the amount (weight) of crap the kids leave permanently in the "trunk".

Just my opinion and experience.

P.S. I also saw the mythbusters that showed that the air resistance of driving on a freeway with the windows down was less fuel efficient than having the windows up and aircon on :-)