Jay Leno: Do these 3 things before buying a used car

When it comes to buying used cars, Jay Leno, host of CNBC's "Jay Leno's Garage," doesn't negotiate.

"The way I negotiate is I say, 'How much for the car? Okay I'll take it,'" he jokes.

That's because when Leno adds a new car to his collection, which consists of more than 100 vehicles, he looks for rare and priceless pieces, such as the McLaren F1 he bought for $800,000 that is now worth $12 million.

"The cars I buy are generally not cars that come up very often," he tells CNBC Make It. "If you think about it like buying art: 'There's only one of these paintings, would you like it?' Yes."

Still, Leno knows a thing or two about recognizing a good deal. Here are three things he says to do before spending money on a used car, especially if it's a collectible.

To Leno, there's no magic formula for determining if a car is too expensive, especially if it's a classic car that he's adding to his collection. Instead it comes down to three factors: "If a car is fun to drive, is of historical or technical interest, and has a style that people find intriguing, then it's probably going to up in value."

Even if you aren't buying a collectible, it's still crucial to do your homework beforehand and have a sense of how much the car you're looking at should cost. You can use tools like Edmunds.com and Kelley Blue Book to research different models, read reviews and do side-by-side comparisons.

"If you're reasonably knowledgeable about cars or motorcycles and you like something, chances are other reasonably knowledgeable people will like it for the same reasons you do," Leno says. "That's what I think makes a car go up in value."

"You always want to get a Carfax report," Leno says. "These are people who know these cars, who check serial numbers and tell you what you've bought."

To pull the Carfax report, you'll need the car's 17-digit vehicle identification number, or VIN, which is assigned to every vehicle in the U.S. The report costs about $40 and provides you with key information about the car, including service and repair information, vehicle registration and reported accidents.

It will give you a good idea of how well-maintained the car is and what kind of issues the previous owner had to deal with.

Used cars are rarely perfect, and every defect you find can help you negotiate the price lower. But make sure it's not anything major. You don't want to turn around and spend all the money you saved on the sticker price fixing extensive issues.

"Find as many faults as you can, faults that hopefully don't include a huge financial outlay to correct," Leno says. "Minor body damage, things of that nature."

For more advice on what to do before buying a used car, check out these articles:

• Time is running out to earn the Chase Sapphire Preferred Card’s huge 80,000-point bonus
• I bought my first car on Craigslist—here's exactly what the process was like in 6 steps
• The No. 1 step to take before buying a car

CNBC's "Jay Leno's Garage″ airs Wednesdays at 10 p.m. ET.

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