And I'm feeling tired, oddly enough. ;)
So, seven states between two cars (some in the family Toyota Prius, some in a rented Chevrolet Impala) and something like 2,000 miles.
I've discovered how rudimentary the Prius' traction control is. Go. Stop. Go. Stop. We averaged something like 49 mph / 49 mpg (US gallons), four up.
The Impala (3.9 V6 4A) needed its traction control and fortunately had an off button for it too. :) 53 mph / 32 mpg, two up... again US gallons.
The Impala used about the same amount of petrol as my four cylinder 1.8 Accord does...