DOUG DEMURO has a wide range of automotive industry experience, from work at a Ferrari dealership to a manager for Porsche North America. A lifelong car enthusiast, Doug's eclectic vehicle purchases include a Porsche 911 Turbo, an E63 AMG wagon, an old Range Rover and a Mercedes Benz G-wagen.

If you're interested in buying a used car, you might be wondering how old is too old when considering a vehicle that meets your needs. We have the answer. There are different options depending on whether you're interested in reliability, safety or equipment, so we've covered all three topics for shoppers thinking about purchasing a used vehicle.

Safety

If you're interested in safety, there are two general rules. The more expensive the car was originally, the better it will be, and the newer the car is, the better it will be.

Keeping those two rules in mind, here are a few general guidelines. Dual air bags became federally mandated for the 1998 model year, which means the vast majority of cars built in 1998 or later will have them. Although anti-lock brakes and side air bags have never been federally mandated, they became widespread in the late 1990s and early 2000s. Thanks to a federal mandate, all cars made after 2007 must have stability control.

What year should you pick? Although it depends on the car, we generally believe the early 2000s are a good place to start your search if you're interested in safety. You'll have front air bags, anti-lock brakes and side air bags, too. We'd check your car's equipment list to ensure those items are included.

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Reliability

If reliability is your top priority, you probably don't want to buy a vehicle that's too old. After all, the older a car is, the less reliable it's likely to be, even if it's a well-maintained, low-mileage vehicle, such as a Toyota or a Honda.

Reliability does depend on the vehicle and how many miles it's covered. We wouldn't go too far beyond the mid- to late-1990s for any car, as parts can be harder to find once a car crests 20 years old. For vehicles with more than 150,000 miles on the odometer, we might recommend trying to find a newer model year than the late 1990s.

Equipment

What if you want the latest and greatest in technology from your used car? Once again, this depends on the vehicle you choose, but generally speaking, newer vehicles will be better than older ones.

For example, 10 years ago heated rear seats were considered a huge luxury reserved for only the most expensive cars. Now, this feature is on the option lists of most family sedans and even some compacts. It's the same story with automatic climate control, an iPod interface, adaptive cruise control, ventilated seats, a panoramic sunroof and many other items once considered luxuries that have become fairly commonplace today.

As a result, we suggest going for the newest possible model you can find if you're looking to maximize your equipment. Our only word of warning: If you choose a high-end luxury car, such as a BMW or a Mercedes, beware of potentially high maintenance bills. These vehicles only get more expensive to own as they grow older.