Z-Car

Hymotion, the company that has been developing a plug-in kit for the Prius, has now started taking deposits for the L5 conversion kit. The kit costs $9,995 plus $400 for shipping and, of course, any applicable taxes. That price includes installation at an approved shop and a three year warranty. The first deliveries and installations should start this July.

The kit consists of a 5kWh battery pack filled with A123 lithium ion cells that fits into any second-generation (2004-2008) Prius. The pack can be fully charged in 4.5 hours at 110V and Hymotion claims a converted Prius will get up to 100mpg for 30-40 miles. Your mileage will of course vary. The pack has been crash tested and meets all current federal safety standards. Hymotion was bought up by A123 last year after doing a number of conversions for fleets and government testing.

http://www.a123systems.com/hymotion

The price on these hop-ups has to come down, 10-12K just to get a little bit more milage is not going to work. Even with gas at $4 a gallon, that takes too long to pay back.