Even if I did install a bigger motor, I wouldn't drive the Zenn on freeways. It's really not safe for highway speeds. In my area I drive city streets at 30 to 35 mph, and there are no hills. From what I've been reading, there should be some highway capable EVs coming out in a couple of years. Chevrolet and perhaps Toyota will be producing plug-in hybrids that will run 30 to 40 miles on electric only.
Thats pretty good. Can you change motors out? I have some freeway and some hills, wish I only needed 4 0r 5 miles.