The Mound of Sound has a reasonable proposition, How about free car insurance for short range electrics? The idea being that you would use one car for short-range use and another for medium to long range commutes beyond the range of the electric. It assumes that there is one driver, but two cars.
I suspect that the average family has more licensed drivers than vehicles (especially once teens get their licenses). So this idea won't work under the transferable licence plate idea put forth.
But, the concept has merit. Reward ownership of a short range electric by offering reduced insurance rates, and lower annual licensing fees (there wouldn't be any bi-annual breathalyzer requirement for an electric.) If the cost of ownership is low enough, its worthwhile enough for the average family. For families in urban areas, usually one adult has a shorter commute. My wife needs a vehicle to get groceries, drop the kids off at school, and do other in town errands. In short, an electric for intra-urban driving would be perfect.
When you factor in that driving only 5-6 kms at a time is really hard on a gasoline powered vehicle, and that city driving is the least efficient use of gasoline, an electric really becomes a no brainer. Electrics have their issues as long range commuters. Range, battery life, power charging times, etc. all are impediments to regular medium to long range driving. With current technology, intra-urban driving is the perfect environment for these vehicles. So why not reward and encourage it?
Speaking of which, bring on the Zenn already!