I noticed this the other day:
A Classic EV Design With Advanced Features
Looking at the Urba Electric design, three Controller designs are mentioned-
1) a modern controller
2) a Voltage Stepper-not as efficient but probably cheaper
3) a CVT transmission to keep the motor at most efficient RPM (possibly with a simple Amp limiter-no details on the page)
I don't have a copy of the plans yet(I plead Extreme Poverty at the moment) but i'm really curious on what effect a current CVT (either mechanical or electronic controlled) would have on a light EV...