Temperature and gas mileage?

[Russell]

It has been almost 100 degrees on my afternoon commute this week. It seems as if my gas mileage has dropped by about 10 percent. I assume this is the HIGHER load than normal on the ac and the heat/hot air reducing engine efficiency. In the morning with cooler temperatures, mileage seems normal. I am using the OBC to check mileage.

Just an observation. I need something to do while driving.

[Derek A.]

A/C takes power. Engine does not make as much power with the warmer less dense air. Generally means you have your foot in the kitchen bit more.

I am going through the same thing.

[MarkD]

It has been almost 100 degrees on my afternoon commute this week. It seems as if my gas mileage has dropped by about 10 percent. I assume this is the HIGHER load than normal on the ac and the heat/hot air reducing engine efficiency. In the morning with cooler temperatures, mileage seems normal. I am using the OBC to check mileage.

Just an observation. I need something to do while driving.

Your a/c is partially contributing to the lower mileage, but as the intake air is much warmer, ignition timing is retarded also. This will cause loss of torque and lower fuel economy.

MarkD

[Russell]

Good point on ignition timing!