When you're in the market for a used car, the Latin phrase caveat emptor ("let the buyer beware") should be the guiding principle behind any purchase. Distinguishing a cream puff from a hard-ridden beater becomes an epic responsibility when so much of your hard-earned money is at stake. So how do you find the right used car? Due diligence is key. Having a plan about what to look for before scouring the Web and the streets in search of that diamond in the rough will help you find a vehicle that will serve as a reliable partner for miles to come.

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Repair history

The more detailed the repair records, the better your understanding of the car's history and its condition. Repair receipts from current and previous owners are great indicators of a vehicle's condition. Allen Otto of Hansville Repair in Hansville, Wash., says to keep an eye out for recently completed big-buck maintenance on high-mileage vehicles; look for items such as timing chain and belt service, water pump replacement and transmission repairs.

Vehicle history

On newer vehicles, it's wise get a history report from services such as Carfax, AutoCheck and Instavin.com. However, Otto says buyers should understand that these reports refer only to insurance claims for incidents such as accidents, vandalism and flood damage, and have little to do with the mechanical operation of your candidate.

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Signs of neglect

Always check a vehicle up and down, inside and out for any signs of damage or previous repair. Something as simple as the cleanliness of the interior can be a crystal ball into the quality of upkeep the vehicle has seen. Keeping a tidy cabin requires no technical ability and it illustrates the current owner's commitment to the vehicle.

MacGyver on duty

Escaping MacGyver-like from a jail cell with a paper clip, rubber band and ballpoint pen is one thing, but finding strange objects at work under the hood of a car is a red flag. Do you see some poorly executed do-it-yourself repairs? These can be another sign of neglect. Do all the tires match? A previous owner who cut corners on maintenance could be setting you up for a big fall.

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A fluid situation

Checking oil and transmission fluid can provide key clues to an engine's internal health. Otto says the oil should not be gritty, watery or milky. Color is irrelevant. An oil-change sticker on the windshield can also provide insight. Transmission fluid is all about smell. An odor of dead fish means at some point the fluid got too hot, which leads to viscosity breakdown and potential damage. Be wary with your nose and also observe how the transmission shifts on your test drive.