Is the Warranty Void When a Dealership Modifies a Car?

Any dealer can install high-performance parts, but not all dealers are manufacturer approved.

Mike Hagerty | 

Oct 21, 2022 | 3 min read

Chevrolet

During the 1960s, a handful of American new-car dealers made themselves famous with automotive enthusiasts by modifying the cars that they sold.

After starting with suspension mods for the rear-engine Corvair, Yenko Chevrolet near Pittsburgh began putting bigger, more powerful V-8 engines in Camaros than Chevrolet was willing to install at the factory. Mr. Norm’s Grand Spaulding Dodge in suburban Chicago did the same with Darts, and Chuck Foulger Ford in suburban Los Angeles was working similar magic on Mustangs (Foulger was Ford’s drag-racing program manager before buying a dealership). Their success inspired other dealers in other cities to do the same.

In that golden age of muscle cars, the factories were cheerleaders of the fully franchised horsepower enhancers. But what about today? Manufacturers are very strict about what an owner can and can’t do (or have done) to a vehicle without supposedly voiding the warranty. Do those rules apply to dealers that make significant modifications, essentially acting as aftermarket tuners before the car is sold?

Manufacturer Warranties May or May Not Remain Intact

While European brands tend to have factory tuners in-house (like Mercedes-Benz’s AMG and BMW’s M), American brands take a different approach. Dodge Direct Connection, Ford Performance, and Chevrolet Performance make high-performance parts ranging from modified computer chips to crate engines, and authorize a select group of their dealers to sell and install them. As long as those factory-built, supplied, and authorized parts are used in the modification of a vehicle, and the work is done by a factory-certified installer, the manufacturers back them with warranties.

The specifics of these warranties vary by manufacturer, but they are overall less generous in terms of years or miles covered because there’s an expectation that the vehicle will see more aggressive use than a typical passenger vehicle. However, assuming there’s no abuse or other violation as defined by the terms of the warranty, repairs would be covered at a dealership. (Although, not all dealerships are part of the factory performance programs, and won’t have specially trained and certified technicians available).

Buying a car modified by a dealership that isn’t part of a factory-authorized program is more complicated. Some dealers offer their own warranties, but those can mean warranty repairs have to be done at that dealership—potentially inconvenient and expensive if repairs are needed while you’re traveling, or nearly impossible if that dealership goes out of business. Another option is to shop around for an extended warranty that covers modifications. It’s a good idea to ask about specialty coverage, too.

It’s Important To Know Your Rights As a Consumer

The Magnuson Moss Warranty Act requires manufacturers to honor the original warranty unless they can prove that the aftermarket modification (either the parts or installation) was responsible for the failure that caused warranty repairs.

Just know that, ultimately, if they say the modifications were responsible, the only way to settle the proof issue is usually in a court of law—and that can be very expensive. If you lose, you’re not only on the hook for the repairs, but also attorney and court fees for yourself and the dealership.

Mike Hagerty

Sorting through the hundreds of new car, truck and SUV choices on the market to find the right one for your needs gets tougher all the time. I'm here to help. I've been writing and talking about new vehicles for 25 years on TV and radio, in print and online. And my passion for cars and driving goes back even farther than that. I love design and performance, but the second-largest purchase most of us will ever make (for some of us, the largest) needs to be based on more than good looks and quick zero-to-60 times.