Most of these services are very similar with possible better/different negotiated discounts... you would probably get a very similar deal through Costco, AAA, or a different Credit Union... all these services just email your info to their dealer network. If you want an actual "car buying service" you need a vehicle broker who (for a fee) searches all over the country for what you want and negotiates for you. Sometimes this is a much better deal even with the broaker fees.