"could get it for under $17...then why they put $21 on it in the first place, "
Sonic dealers ie GM, don't offer straight up pricing, they offer deals on jacked up List prices. They market to a specific type of person whose math skills aren't great and simply blow them away with a large discount on an inflated starting price. One salesman remarked to me that the biggest difference he noticed when he went to Toyota was that customers walking in were totally different people from those he encountered in the GM showroom.
Most brands probably do this from time to time but it has been standard GM practice for many years. I think it is exploitive but, at this time, it is legal.
One fellow I know bought a loaded truck for something like $45k - they gave him $10k off because "someone had put a deposit on it and then walked". Of course, there were other customers about to jump on it according to the salesman. He couldn't believe the deal and bought on the spot.
If you pay full list for a GM or remotely close, you've been had.
Cheers and Happy New Year,
John M.
