One in four millennial car buyers don't feel comfortable negotiating a car deal, according to a survey commissioned by Cars.com. But millennials have a penchant for online research. Here are five key ways to connect data to car bargaining.

Budget first

Younger car buyers should understand how the monthly payments will fit into their budgets. Understand that your total car costs will be more than your monthly car payment. The total car price includes other factors, like gas and insurance, not just the monthly payment.

Get preapproved

On the lot, a salesperson might not take a millennial car buyer seriously. With a preapproved auto loan offer, you will not only know how much you can afford to spend, but you can negotiate as a cash buyer. And you can probably get the dealer to beat your rate.

Be price savvy

Knowing the current market value of a car is the best starting point for negotiating. Check online pricing guides to find the average transaction cost for the car you want to buy. This allows a young car buyer, who might lack confidence, to depersonalize the negotiation by pointing to a neutral source.

Know the car's history

If you're buying a used car, getting a reliable vehicle history report is well worth the small fee. Any negatives on the report — a minor crash or multiple owners — could be used as a bargaining chip in negotiations. Carfax and AutoCheck both provide individual reports or short-term deals for multiple reports.

Take your time

Inexperienced car buyers might think they are done negotiating once they have settled on a price with the salesperson. Instead, they are handed off to a more formal finance manager. That's when warranties and services are tossed your way. You don't need to make a decision right then. Take your time when closing the deal.