Cartelligent is similar in the sense that it provides a very convenient way to buy a new car. They are a lot more hands-on than CarWoo! (in fact, they are a broker, while CarWoo! is not), so the buyer won't ever actually talk to a dealer and Cartelligent usually will deliver your car to your house for you. However, it costs at least an order of magnitude more than CarWoo! ($500+ vs. $49).
Given that their business model doesn't scale very well, they've never expanded out of California, and only recently (after being around for 10+ years) expanded out of Northern California. CarWoo!, on the other hand, can help buyers anywhere in the US.