An India-based company called Electric Motors and Vehicles has developed what they believe is a great intermediate solution to EV range anxiety before a real network of EV charging stations is built. The concept is called the Pru and it's a self-propelled trailer containing an electric generator and batteries that attaches to an EV and keeps it charged on longer trips.
The creators of the Pru think that EV charging infrastructure won't grow as quickly as its needed with the introduction of new EVs on the road. The Pru trailer, with its lithium ion batteries and 750 cc diesel generator, could allow an EV driver to go 700 miles on six gallons of fuel -- a fuel economy of about 116 mpg.
The trailer would propel itself with a 240V DC motor, always matching the car's speed so there is no stress on the car's motor. It would connect via a "Smart Hitch" that would send signals to the speed controller based on the tugging or tension on the hitch. A GPS unit would analyze the route's typography to maximize battery efficiency.
To top it off, the batteries and generator only take up a fourth of the storage space in the trailer. The rest is left for whatever stuff you need to carry on your trip.
The Pru is still just a concept with no prototype produced yet, but the company thinks that units will be ready by early 2011 and at a cost of about $15,000.