Most of the things make sense, except for the part on financing where the dealer supposedly jacks you on financing. I can't believe a single ounce of that is true for a variety of reasons:
1) Most dealers will finance you with the manufacturer's financing arm such as GMAC, HMAC, etc... The dealers will recieve no part of the financing proceeds. Your credit will determine your interest rate, not the dealer's. I've personally never heard of anyone with good credit being financed over 9%, even in the boom times of the 90's.
2) Most dealers will not finance you internally. Think about it, if you're selling AND financing the cars, the dealers would have to have an incredible amount of assets, which most won't.
3) If you're financed with a bank, the dealer will receive a referral fee based on the aggregate loan amount, independent of the interest rate being charged. In accordance of fair lending laws you are able to see the lender's criteria for assigning your interest rate. Thus banks can't merely stick it to you, and most won't.