Trip mileage

[Barry Wolk]

What's your trip mileage. I got 15 on a trip across Michigan at 70 mph. Should I be getting any more than that?

[Mad Scientist]

That sounds about right.
I seem to recall that on a trip out to Colorado with my parents, many years ago, my father said that is what he was getting and consider that to be pretty good for car 5000lb car.