Dealership advertising laws require a vin/stock number and an expiration date to come along with all price offers. This protects the consumer from bait and switch problems which are rampant in this space. Without these protections dealers and vendors can simply make up prices to draw people into the store and when they show, switch them to something else.
I understand in depth the challenges involved in doing this right from a product standpoint and it would be orders of magnitude easier to provide a product that doesn't include a vin/stock number (a topic for another post). But the problem is consumer perception is wrong and misleading. If someone comes to my product and car buyers can get prices on a vehicle that may or may not exist (no vin/stock number) you are enabling bait and switch scenarios. On CarWoo! you will not have this problem, all offers have a VIN/Stock number and an expiration date.
Brokering laws (getting paid a referral fee from the dealer when someone you sent to the dealership sells a car) are also in place to protect the consumer. I had one of our ex-dealers that work for us explain this to me, because at first I didn't understand why this was a consumer protection issue. He used this example. It may be a bit out of date, but it illustrates the point. Let's say you're in a town with three or four car dealerships and the preacher in the town establishes a relationship with one of the dealers where the dealer will pay the preacher $500 for every customer the preacher sends their way that buys a car. On Sunday this preacher uses his influence to recommend people should buy from his favorite car dealer. The people in the congregation listen and when they go to buy a car, they go to the preacher's favorite dealer. The preacher gets paid, the dealer marks up the car $500 to pay the dealer and the consumer essentially paid $500 more than they had to. The brokering laws are in place so disclosure about the financial relationship between the buyer, the dealer and the broker are transparent.
Essentially you can get a better deal as a buyer without a broker and you should know upfront that's the case.
Hope this helps, it's taken me four years to understand all this stuff.