(MONEY Magazine) – THE LAW When you start with a big purchase, all the ones that follow seem a lot smaller. That's how the car industry takes the sting out of the extra cash you'll have to shell out for your ride. But there are some ways to get all you need and still make a clean getaway.

It's (most likely) the second-biggest purchase you're ever going to make. And that doesn't even count the cost of keeping your car well-equipped and well-maintained. With so many things to spend money on, the experience of buying and owning a car is riddled with hidden costs. After all, when you start with something that costs in the tens of thousands of dollars, a couple hundred here or there doesn't stand out as much. Options can add up, contracts can be impenetrable, and (shockingly) some people in the business may not have your best interests at heart. Here's how to stay on the straight and narrow.

ITEM PRE-OWNED VEHICLE

TESTIMONY All "certified" cars are thoroughly inspected and reconditioned.

REBUTTAL It makes a big difference who's certifying it. Dealer-certified vehicles are generally just used cars with an extended-service contract rolled into the sale price. Such cars may or may not have been inspected, and the service contract could have more holes than Pebble Beach.

VERDICT Make sure you're dealing with factory certification programs. And make sure your ride-to-be has a bulletproof reliability record (such as Acura's TL sedan, above, which is a hoot to drive and built to last).

ITEM IN-CAR NAVIGATION SYSTEM

TESTIMONY When you're picking options for a new car, you should spring for the factory-installed navigation package.

REBUTTAL Factory systems are well-integrated, but they rarely cost less than around $2,000. That's a pretty exorbitant charge when most of the key features are now available in after-market systems that can cost anywhere from $400 to just over $1,000. Some even add features most factory-installed systems don't have, such as real-time traffic information, and most are portable, so you can transfer a device from car to car.

VERDICT Check out Garmin's StreetPilot c550. It's reliable and easy to use, and it has a built-in traffic receiver that can route you out of trouble. With its wireless speakerphone and MP3 player, it's a good buy at $800. If you want to skip the built-in traffic routing and the gadgety perks, Garmin's c530 is a solid performer at $600.

EXPERT WITNESS

ITEM AUTO REPAIR

DOUGLAS FLINT, owner of a Virginia repair shop

"Never use the words 'Do whatever it needs' in a garage unless you really mean it. If you are going to be too busy for the shop to reach you, set an approximate dollar figure that's not to be exceeded without your further approval. Also, be wary of the big "fluid flush" that is becoming the standard of the industry. Fluid flushes are vastly overperformed these days or, worse yet, sold and not performed because they're too much trouble and the fluid looked okay anyway. Another thing: Don't be afraid to get a second opinion--if something sounds fishy, it may very well be. Oh, and you know that old trick of leaving a $20 bill under a floor mat or between the seats to test your mechanic's honesty? Forget it. Everyone in the business knows about that one."

Additional Reporting By Asa Fitch, Michelle Kalkhoff and Ingrid Tharasook contributed to this article.