On Sun, 16 Jun 2013 22:12:33 -0400, "Eisboch" wrote:

This is pretty simple but I can't figure out what I am doing wrong:

Bought a 2002 Saturn for a kick around town car. It's a Canadian
car, so the odometer reads in kilometers instead of miles. It's a
very basic car and you can't set it to read in miles.

So, the day I picked it up it had a quarter of a tank of gas. I
stopped at the gas station and put in $20 worth. At $3.68/gal that
amounts to about 5.4 gallons. It brought the gauge up to about 3/4
full.

Drove the car around for over a week until the gauge read a quarter
tank again. According to the odometer, I had travelled 700
kilometers.

1 kilometer equals 0.62 miles. So, 700 kilometers time 0.62 equals
434 miles.

Divide 434 miles by the 5.4 gallons I had burned and it says the car
is getting about 80 miles per gallon !!!

I was just trying to get a rough idea of what kind of mileage it gets,
but this can't be right. What am I doing wrong? I feel like an
idiot.

=====

Most odometers are reasonably accurate and your conversion
calculations are correct so the issue is likely to be with the fuel
measurement. The best way to calculate mpg is between fill ups since
that takes the gas gauge out of the equation. With a small tank
you'll probably need to take the average of several different fill ups
to get an accurate number.