The dealers are only as clued up a they can be arsed to, if they really want to know all things about the cars they sell then every possible scrap of information is available to them through their own network, the problem is that to gain the knowledge they would have to spend time researching the info and more time actually reading it when all they really care about is how many sales they can get and how much money they can make, I bet not one of the staff has done any extra research out of office hours ever!