The TrueCar service app is not a scam but rather is a program that offers its users a chance to bid at lower prices for dealership vehicles. TrueCar is free to use for its users, and it makes a commission from each car that it sells through the website. The respective dealership pays this commission.
The TrueCar app offers free services to the public with the intent of making the process of buying a vehicle easier. It gathers recent purchase history from several affiliated dealerships and shows the prices to prospective buyers. Buyers then have the opportunity to bid against each other for the car, and the person with the highest offer buys it.