Theory:
If my tank holds 10 gallons and I drive 250 miles before it runs dry, my mpg
is 25 MPG.

If my tanks holds 10 gallons, say I let it idle in my driveway for 3 hours
and then start the trip.  My tank would run dry at 225 miles.  My true mpg
would be 22.5, BUT I used x (unknown qty of fuel) during the 3 hour idle.
Since the engine does not idle on pure air, the amount of fuel used is
negligable.

In short, no matter what my driving habits ove rthe course of a year my mpg
averaged 25 MPG +/- 1 MPG.

.

Mark Rokus wrote:

> Steven Broomhead wrote:
>
> > .  The mpg was irrespective of highway driving, stop and go driving,
> > or just idling in my driveway waiting for a warm vanagon to climb into.
> >
>
> I've never been able to figure out mileage while in my driveway.... How
> exactly is that done?
> :-)
> Mark