A group of 100 auto dealerships that are part of TrueCar's network are suing the online car-buying service for not disclosing to consumers the nature of the fees that dealers pay the company for each sale. The suit, filed today in state court in Los Angeles, alleges that TrueCar is engaged in "deceptive business practices" because its advertising touts transparent pricing but doesn't disclose the transactions fees of $299 for new cars and $399 for used cars that many dealers pay TrueCar for each sale handled through the buying service.