I got in to a rather contentious fight with a dealer based on TrueCar a few years ago. Dealer internet sales quoted me MSRP less "no qualification rebates" and no additional discounts. TrueCar for same trim/color/options was a discounted price, less the same rebates, for a price that was $3,000 less than the dealer. I asked the dealer if they would match TrueCar. They claimed the price they gave me was less than TrueCar. I told them it wasn't, they basically said "Impossible! Prove it with screen shots!". I sent the screen shots. The dealer replied that they discussed the TrueCar pricing with the general manager, offered NO commitment to match it, and then proceeded to ask me when I would like to take delivery. Needless to say I had no interest in dealing with them after that.
TrueCar is just like any other lead generation service. They pretend to be acting in the best interest of the buyer, but are nothing more than a portal for sales generation. The car buying service my car insurance offers uses TrueCar as their platform. Before you can get a final price quote, you have to agree to transmit your contact info to at least one local affiliated dealer (who will call you within 20 minutes of hitting the OK button...and then call you every day thereafter until you tell them you are just shopping or no longer in the market.)