A few months ago I purchased a Certified Pre-Owned BMW for my wife. When I asked the salesman about using a credit card, he had to call the sales manager over. The sales manager told me that the back office would only allow $2500 on a credit card. After a little more discussion, I was able to get him to sign off on using my Skymiles AMEX for $7500. This was enough to get me to the next 10000 Medallion qualifying mile threshhold.