I've used carbargains in the past and it worked very well. The service is almost identical to CarWoo's but they have been around longer.
http://www.checkbook.org/auto/carbarg.cfm
Schmidt, F.L. & Hunter, J.E. (1998) The validity and utility of selection methods in personnel psychology: Practical and theoretical implications of 85 years of research findings,” Psychological Bulletin,
They still need to work on their pricing. They have an opportunity to convert quite a few of their non-paying customers if they'd simply offer a plan between 2GB and 50GB.
This type of car-buying service is really convenient. When I bought my car a few years ago I used a service called CarBargains and ended up saving around $4k. IIRC CarBargains cost $200 vs CarWoo's $39.
Does anyone know why they haven't implemented the ability to insert good old-fashioned hyperlinks? Links embedded in the text would save some characters in the message and improve legibility.
Part of the BusinessWeek article on Bloom from last December discusses emissions: "Though the technology consumes hydrocarbons, Sridhar says, it doesn't involve carbon-releasing combustion, so it emits only about half the greenhouse gases of conventional energy sources."