Two things that happened to me when I bought my current car (a BMW as it happens, bagold, from Foreign Motors West near Boston) but it could be any car, anywhere) -

1. I tried to pay with AmEx (having previously verified that the charge would go through). They balked. I pointed out, politely, that their contract with AmEx requires them to take it as payment for any transaction and that there were no signs posted, nor was I given any other notice, to the contrary. They offered me LoJack ($695) free if I'd pay some other way. Since I had ordered it anyway, the value was about a wash for me but much cheaper for them, and I expected a long-term relationship, I took it.

2. I was supposed to get miles under AA's fly2buy (one mile for each $4) program. They didn't come through. The dealer kept calling and faxing; no results. I finally suggested this: I'd buy enough Corn Flakes in airplane boxes, they'd reimburse me, I'd donate the cereal to a local food bank and send in the coupons. It worked for everyone. (The funniest part was explaining to the supermarket people why, when the cereal arrived from the warehouse, that I wouldn't take them if they didn't have airplanes on the boxes.)

Bagold - enjoy your car. I love mine!