When I bought my used Mini Cooper in April, things didn't go exactly as I'd planned. Part of this was because I hadn't done enough research. But a lot of it was because the dealer had some tricks up its sleeve and I did not.

At Car and Driver, Jared Gall has compiled a list of car dealer tricks to watch for when buying a vehicle. He says that the following are common practices:

• • Juggling the foursquare. The “foursquare” is the worksheet on which the salesperson jots down the terms of the deal. It's an easy way for her to manipulate one factor (purchase price, down payment, monthly payments, trade-in value) or another.

• • Profiting from rebates. Gall warns that salespeople often use the presence of a rebate to manipulate buyer psychology. Don't let that happen to you.

• • Inflating payments. The more you're willing to pay each month, the more room the salesperson has to work. The article recommends ignoring the question of monthly payments until you've negotiated the price of the vehicle.

• • Fees and extras. “If it's anything he offers after you've negotiated your sales price, you don't need it and shouldn't pay for it.”

• • Interest-rate bumping. Gall recommends shopping for your own financing before you shop for a vehicle. He also warns that “it is not uncommon for the dealership to secure financing for you at one APR but offer you a rate one percentage point higher — and then pocket the difference.” Be careful. 
  • Altering the bill of sale. Some dealers will leave the contract open-ended. Don't allow this. Don't sign anything with blanks or undefined terms. Be sure the paperwork is complete before you leave the lot.

Gall says there are several other tricks that dealers use, though these are especially underhanded. “If a dealership pulls any of these stunts on you, it doesn't deserve your business,” he writes.

• Ransoming your check.
• Eavesdropping.
• Lying about your credit score.
• Misplacing trade-in keys.

For more information on these tricks and how to cope with them, check out the full article at Car and Driver.

The dealer trick that got me isn't on Gall's list. When I went to look at my Mini Cooper, I was greeted by a young man who'd only been on the job for two weeks. After I test drove the car, we sat down to negotiate. I talked him down from $17,000 to $15,000 and was very pleased with myself. But then he fetched the “closer”, whose sole task was to talk me up from that $15,000 number. I had essentially told the dealer how much I was willing to pay, and the closer was there to get me to pay more. And I did. I paid $15,600.

The young salesman did a follow-up call a week after I bought the car. He was doing a survey to ask me about my experience. I told him it was fine except that I didn't like dealing with the closer. I felt like I had been manipulated by him. “Yeah,” he said. “You shouldn't listen to him. He talks a lot, but he's full of shit. He wants to sell that car. You had more power in that situation than you think.”

Lesson learned.