hello all,

A nice side effect of summer in California that I realized is now my car seems to be giving much better mileage than before even with the AC on most of the times. In previous months, the mileage was about 18-20 and now after summer started I dont see anything less than 21 and one time it was 25 mpg. Any comments on this?

1994 E320. I generally always fill upat Arco on Automall-S.Grimmer, Fremont, CA

Regards,
Kalyan

Yes. Warm air is less dense than cold air. That is why hot air balloons rise and airplanes need longer runway distance in hotter weather. Air resistance is a dominating factor in energy loss at highway speeds. I get about 10% better mileage when it's 80 vs. when it's 60.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra

The engine warms up faster during the summer, so it does not need extra fuel (e.g. "choke") for as long when started cold. If you do mostly short trips & city driving (which I suspect is the case, based on the posted MPG numbers) this is also a factor.

- JimY

Warm air is less dense than cold air.

Less dense == less oxygen

Less oxygen == less fuel needed for stoichiometric burn.

Winter/summer gasoline formulations make a difference too.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles