I think a couple of things are going on here.

1. As mentioned before, a higher altitude means less horsepower, so it helps the MPG by *not* giving you full power when you floor it.

2. Air density. I dragged out my flight computer and did some calculations based on 5000' @ 15 Celsius. At 78MPH(ground speed), your Airspeed is only 70. Less wind resistance means better mileage, and I would guess the EV's have a very large frontal area.

-d

At 11:24 AM 10/29/99 -0600, you wrote:
>re:  At altitude that air density becomes less and less in relation to
>the amount of  fuel going through the engine, so fuel air mixture goes
>to the rich side ...
>
>Think the air mass sensor compensates and this is only true with
>carburetors.
>
>re:  i've definitely noticed increased gas mileage at altitude ...
>
>Less air, compensated by air mass sensor equals less fuel (and less
>horsepower) and certainly should equal more mpg.  It also means less
>compression since air is less dense to start with, meaning less octane
>requirement.
>
>