Congrats on the new car, it's much easier to joke around when you're prepared and they know it. I was going to add that the other mental tricks they try is with your credit report (Not that it mattered to you since you weren't financing with them), I've seen bosses show people's credit report to customers who weren't familar with the approval process/credit reports, etc. and all he had to do was point out late payments from 3-4 years ago, "Here's a 30 day late...another 30 day late...60 days here..." and by the time he's done the customer went from assured he would be approved to "oooh man, please - do I stand any chance of getting approved??? Help me!", by that time you'd better walk out because they have you and can get you to sign for any interest rate, 14%, 16%, etc.
Most banks only care about what you did in the past 2 years (Except for unpaid collections, bankruptcies, etc.) I would always pull my credit report before going out and getting an idea what your credit score is. Anything in the low 600's would need something down...unless you have a history of car loans and they're all good, in which case you shouldn't budge. 650 is pretty much a sure thing and 680 + is automatic. If you have a good payment history for 2 years then you have nothing to worry about. And finally, if they pull the stunt that "Cars are harder to get approved for than credit cards" then laugh. Cars, homes are secured loans, i.e. you don't pay they take away your car, home, etc. Credit cards are unsecured, thereby harder...