Why Do Modifications Tend To Hurt Car Values? | Autance

This is one case when knowing what you have is completely useless.

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Why Do Modifications Tend To Hurt Car Values? | Autance © Why Do Modifications Tend To Hurt Car Values? | Autance

People love customizing things, especially cars. If you put a new car into the right hands, it can be tuned and transformed into something truly special with ingenuity, creativity, and a lot of money. When it’s time to sell that vehicle, however, the money poured in does not always add up to a better price tag. Contrary to what you might believe, custom cars can be worth less than they were before the modifications and may be harder to sell. Why is that?

Car Autance’ editors have sunk enough hard-earned cash into hopeless cars, so we can tell you why. People don’t always share your tastes, folks can be concerned with reliability issues, and sometimes people just want a stock car. In any case, we’re here to help give you a better understanding of why car modifications can negatively impact your resale value.

Let’s get rolling.

Not everyone shares your taste.

What Are Mods?

It’s important to elaborate on what we mean when we say mods or modifications. We’re not talking about those mean stick-on chrome vents you got from Pep Boys. Those aren’t great, either, but we’re talking primarily about modifications to a car’s drivetrain, electrical system, suspension (including tires and brakes), or other changes that the owner performs outside of the realm of factory-designed and installed parts. And although it’s not a hard and fast rule, mods generally mean changes to the car that can’t be installed or removed without tools and time. 

Why Do People Modify Cars?

People have been modifying cars since the dawn of the car. Manufacturers design vehicles to perform a certain way, and while they know what they’re doing, they don’t always realize a car’s full potential. Want to accelerate more quickly, stop in a shorter distance, or improve nighttime visibility? You’re looking at mods. In the same vein, adding a lift kit for better off-road performance or installing aftermarket subwoofers for more bass are considered mods. It’s about tailoring the car to suit the owner’s desires.

Sometimes mods aren’t intended to make a car a better performer, they’re merely cosmetic improvements. People add larger wheels, custom paint jobs, and upgrade interior finishes to accomplish this. For simplicity’s sake, we could classify the installation of a hydraulics system as cosmetic, too. Mods make a car more personal rather than driving something thousands of other people drive, but that personalization can come at a cost.

Why Do Mods Tend To Devalue Used Cars?

Imagine moving into your first apartment. Assuming you could do so without incurring the wrath of your landlord, you immediately started painting. When you move out, you probably will be required to change the walls back to white or whatever they were before. Your landlord wasn’t being picky. This is to ensure that the next person viewing the apartment isn’t turned off by your color choices. 

The same is true for cars. Your primer-colored, extremely loud, 1995 Honda Civic may mean the world to you because you built it, but the next buyer might not want anything to do with that homebrew catback exhaust and the clear taillights you added. By design, mods are personal and meant to enhance the car in a specific way for a specific person. This is even more important when you’ve made multiple modifications to a car, making it completely different from how it started its life. You might find another person who loves the mods as much as you do, but the market for modified cars is much slimmer than it is for stock cars. 

“Modifications are mostly based on the tastes of the current owner,” said Steven Lang, used-car master and a former contributor to The Drive and Dashboard Light. “Unfortunately for them, nearly everybody else looking at that car will not have those same tastes. That’s why you can almost never get your money back once you modify a car or truck.”

Lang said the quality of the mods is also a factor in resale. “Most modifications are made of cheaper materials than those they replace. In more cases than not, that component will be less reliable than the OEM version.”

Remember that sinking thousands of dollars into mods for a car doesn’t mean you’re going to get it back. Anyone who has ever watched “Pawn Stars” has likely seen someone with a custom-built motorcycle or car being offered $35 for something that cost $50,000 to build. Mods do not equal added value.

Wheels and tires are bolt-ons, and can be removed at any time.

Car Autance’ Glossary for Car Mods

Mods is a general term that includes an endless list of car parts and add-ons. Here are a few of the most common mods you might encounter, plus a few related terms. 


Bolt-on mods are those that don’t require serious tools or installation effort to add. They can be parts such as cold-air intakes or upgraded headlights. When it’s time to sell the car, bolt-ons can be removed without much effort to return the car to its stock condition.


A catback, or catalytic converter-back exhaust, is installed behind the catalytic converter in a car and does not modify the headers or other components ahead of it in the exhaust flow. While they can increase power, catback exhausts are frequently used to increase a car’s aural volume or to give it a deeper, more powerful sound.

Engine Swap

Engine swaps are exactly what they sound like: removing one engine from the vehicle and replacing it with another. In most cases, this involves swapping the gearbox, wiring, and electronics at the same time. If the replacement engine is much larger than the original mill, the engine bay, suspension, and bodywork may need to be modified to accommodate the added size and weight.

Smog Check

Many states require that vehicles manufactured after a certain date pass a pre-registration test to ensure that their emissions systems are working properly. This can involve a check of exhaust gases, the fuel system, and more. Some modifications, especially those that change the exhaust system or vehicle computer, tend to cause vehicles to fail smog checks. This can be caused by a mod that alters the way emissions exit the vehicle. In this way, your chosen modification may be illegal in your area.

Pre-Purchase Inspection

When you’re getting ready to buy a car, modified or not, you should have it checked out by an independent mechanic or shop. You should trust the car’s seller, of course, but there may be underlying issues that they are not aware of, and a pre-purchase inspection could save you thousands of dollars in unwanted repairs to a car that you should have passed on.

The Car Autance Questionnaire

Q: How can I tell if a used car is modded?

A: In many cases, you’ll be able to see the mods, especially if they are on a car’s exterior, but just as many will require a look under the hood. Some signs include brightly colored parts such as hoses or covers, random wiring, superfluous splicing and tape, extra zip ties, parts with advertised brand names, or things that don’t fit properly. 

We recommend having a vehicle inspected by an independent shop or mechanic before purchasing. A pre-purchase inspection will give you a chance to have an experienced mechanic find any mods and let you know their condition, how well they were installed, and whether or not they impact a car’s value.

Q: Are there any modifications that increase a car’s value?

A: In very limited circumstances, a mod can increase a car’s value but not for the reasons you might think. We’re talking about mods that correct a known flaw or that offer preventative maintenance for an issue that a vehicle commonly experiences. Think of the IMS bearings on a Porsche 996 911, for instance, which are known to be a common point of failure. 

A: Nearly all states have laws that prohibit certain types of car mods, such as removing exhaust components or disabling safety equipment. That doesn’t mean you can’t or shouldn’t modify your car. It just means that you should do research on what will and won’t get you a ticket. 

Q: Are bolt-on mods really worth it?

A: Absolutely. Adding new tires and brakes can change your car’s entire personality and aren’t permanent additions. As much as people love to hate them, catback exhausts and cold-air intakes do really work, but you’ll need to do your research there. Best of all, every one of those mods can be taken off before you try to sell the car.

Q: Is there a good place to sell a modified car?

A: Depending on what you’ve got, there are quite a few great options. Cars and Bids and Bring a Trailer are good for lightly modified or resto-modded cars, Racing Junk is great if you’ve built a homebrew race car, and Craigslist can be good if you want a local sale.

Learn More in this Video about Car Mods

Modifying your car? You’ll need tools and parts to get you started, but it can be hard to figure out where to begin your search. Car Autance’ editors have grabbed a few of their favorites to get your project rolling smoothly. They include Mechanix Work Gloves, Pro-Lift Jack Stands, and Safe Handler Protective Glasses.

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