"Maybe I'm just a fat, ham-fisted, suburbanite, and I should be happy with 60mpg? I just thought flogging it I should get 70, and milking it i'd get 90mpg."
Join the club!
There's a fascinating website at www.craigvetter.com
where he has a long story of trying to improve on a Honda Helix to get better mileage at speed. A failure ultimately, but a lot of info and fun.
Scooting around the neighborhood, parking where you want, and generally smiling your way to work is what it's all about. Don't overthink the whole deal.