Grapeking

Wow! were you going downhill the entire way?

fEArmE

Some uphill and downhill but mostly level!

Vodka G

I was doing about 31mpg from LA to SD going around 75mph

DB22

A better indication would be the long term average from the on board computer times the inherent over-zealous reading.
My average is reading 28 MPG for the last 10000 miles.

NABS4

Which is still not accurate give the optimistic nature of the computer. The most accurate way to measure fuel economy is to calculate it by hand over a number of fiiils.

DB22

Hence:

long term average from the on board computer times the inherent over-zealous reading.

I agree to your most accurate method but it's like worrying about gas prices, you can't do anything about it so just pay up.
The computer on board, even though it may be optimistic, is still good for a relative reading and it does show if your driving habits change or if your car is becoming less efficient with age.
I am still getting better economy and performance from my A6 than I have had with any other car and it has the smallest displacement.

dougpaper

2012 A6 prestige with 67,000 miles now and a Apr stage 1 tune and now a stage 2 with new pulley and just got back today Pittburgh to Jacksonville nc, average on i-95 80 and my whole weekend average is 31.

Got more power and better mileage with the tune.

What a car.

Fithian

I once got 199 mpg in Colorado for 8 miles. (Driving down Mt. Evans)