That's not a tip. It's a "processing fee" assessed by credit card companies (a revenue stream). The 3% charged on top of a large purchase like a vehicle goes to the payment processing provider (the credit card company). To cover the cost of professing fees, most dealerships often offer a cash discount (meaning they will quote a lower price if paid by check).

1. The guy who owns the dealership doesn't get the credit card fee

2. If they charge you extra for using a credit card, they're breaking even

3. If they _don't_ charge you extra for using a credit card, they're paying 3% of the purchase cost to the credit card company (so, $1,000+)

So yes, it's a dick move to pay via credit card for any purchase in the thousands of dollars, if you have the option to pay by check or debit card. I always offer to pay by check if I know the money for the CC will come out of their pocket.