I'd create something like the Volkswagen Nils concept - or just patiently wait for VW to go through with it themselves.
Small, one-seat, lightweight, electric power, futuristic looks, should be pretty good fun to drive. All I need in a commuter, but with a bit of quality to it.
Failing that, a first-gen Insight with the second-gen Insight's drivetrain would be an interesting idea. A little more weight and no lean burn, but useful extra power, still very clean emissions-wise, and still the potential for great economy - given the engine would be pulling the best part of 350kg/770lbs less, the performance/economy balance would still be pretty good.