I've had a Honda Insight since 1999. s/n 152. Good car. It has a good suite of efficiency readouts. The lifetime mpg is about 55, pretty good. It's got a 5-speed manual transmission, a dinky 1 liter 3-cylinder engine, zero-RPM "idle," and an 18hp electric motor (on the engine side of the clutch and transmission) that serves as the hybrid motor, the regenerator, and the starter for the engine.

The ammeter readout (labeled "Charge -- Discharge") trained me to optimize both acceleration and regenerative braking pretty well. Regenerative braking cuts out at 30mph in fifth gear. This isn't documented anyplace, but it's easy to sort out from the ammeter.

I'll tell you, though, this Insight's design is uncompromising in saving gross weight, and I think a lot of the efficiency comes from the low weight. I have a fat friend. When we ride together places, efficiency goes down to 45 mpg. (And no, I don't hassle him about it, in case you were wondering.)