For what it's worth....
I recently bought a KIA and wanted to put it on credit card (that's all I had with me at time of purchase - no checks! They wanted to only take $3000 and said I could get a cash advance for the balance. After some discussion the finance manager indicated they might be able to take $3000 on several credit cards but wanted to check with the owner. I gave them 4 credit cards and authorization for charges up to $3000 on each. I left with the car. Called in the next few days and said cash advance would cost me too much - want to pay with credit card. Anyway - they hemmed and hawed and I had to keep calling but they eventually put it all on the various credit cards we had given them. Unfortunately - not all were mileage cards. But, to the good - $6848 got charged to a Citi cash returns card which was under the 5% back promo period , 3000 to AmEx, 3000 to AA miles, and, this one made my husband happy - 3000 to Harley Davidson Visa. I kick myself that I didn't put all my Citibank AAdvantage cards in my wallet that day but....something is better than nothing!