15.0 mpg to 21.6 mpg!

A 30 or 40 mile run really is nothing. You need to put at least 250 miles on it before filling. I can take my '03 mini van and go on a flat road 25 miles at 55 mph and get almost 27 mpg. If I average it for a whole tank on the road, I'm lucky to get 23 mpg.