[serialk11r]

Originally Posted by niky

Here's some data that actually backs up MetroMPG's testing:

The mpg mythbusters | Auto Express

As far as the speed thing goes, I think that actually could go either way. The EPA says in "city" driving your engine tends to be running at higher loads and thus more efficiently. Thus if you buy my argument, it makes sense that on the freeway you'd be using less gas to run the AC.

In that test in particular, I'd expect the "city" portion to go badly as it did. Idle goes up, engine cycling up to 3000rpm (and thus running the compressor very fast) are all going to sap a lot of fuel.