The Most Illegal Car Accessories and Mods in the U.S.

So, you’re exploring the options to mod your car and make it stand out? Whether you’re a seasoned gearhead or just getting started, you’ll get some value from this article.

I’m tackling a topic that will raise some eyebrows: the most illegal car accessories and mods in the United States.

You might be surprised to learn about some alterations against the law!

I’ve modified all my cars, including a BMW E38, SRT Challenger, and Tesla Model 3, to name a few. Trust me; it’s very easy to break the law unknowingly. Although I’ve never gone over the top, I learned the hard way about some illegal car mods.

Good job on doing some research before you start your customization journey. I also did plenty to write this piece.

There are many unlawful vehicle customizations, and each state across the U.S. has different laws and regulations. Getting more familiar with those will keep you out of trouble.

What Are Illegal Car Accessories and Modifications?

Illegal accessories and modifications are common on American roads despite being banned by law. These can range from seemingly harmless enhancements like wheel spacers to performance boosters that can put you and other drivers at risk.

Anything that doesn’t comply with the federal rules governing vehicle safety and environmental standards can get you in trouble. So, let’s dive into the murky waters of automotive law and discuss the enhancements that can have consequences.

Most Illegal Car Accessories

In the United States, certain accessories are illegal to use while driving. There are various reasons, like safety concerns and violation of federal or local laws. Here are some of the most common examples:

Radar Detectors

Radar detectors can detect police radar guns and alert you to their presence so you can avoid getting a speeding ticket. I’m sure you didn’t know that…lol. According to WiseVoter, radar detectors are legal to own and use in all states apart from Mississippi and Virginia.

However, there are some grey areas.

For example, federal law prohibits using radar detectors for commercial vehicles (gross vehicle weight rating of 10,001 pounds or more). Some states don’t allow the use of radar detectors around schools, and in California, you’ll get a ticket if your radar detector is mounted on the windshield.

Laser Jammers

Laser jammers interfere with police laser guns and prevent them from accurately measuring a vehicle’s speed. While those aren’t yet banned by federal law, a laser jammer can get you in trouble due to the use of unregulated radio signals.

The use of laser jammers is not allowed by state law in California, Colorado, Illinois, Minnesota, Nebraska, Oklahoma, South Carolina, Tennessee, Texas, Utah, Virginia, and Washington—something to remember if you like long road trips across the country.

License Plate Frame

License plate frames are prevalent among car owners. While using cool frames for protection or enhancement is trendy, those may get you pulled over. I recommend you get familiar with the license plate frame laws of your state, but here are the general requirements:

• Your license plate should be valid.

• Your license plates must be free of obstruction.

• All numbers, letters, and identifying markers must be visible.

I’m sure you’ve also heard about the automatic license plate covers, also called ghost plates. Those are marketed as protection against identity theft, but let’s be honest; most folks use them to make their license plates invisible to speed cameras.

Loud Sound System

We all love summer road trips with the windows down and the volume up. While federal laws don’t have a problem with your car stereo, local law enforcement officers might do. They’ll call it noise pollution.

Most states have laws prohibiting noise that citizens can hear from a certain distance, and yes, those apply to loud car audio systems. Typically, that would be 50 feet and even 25 feet in Florida, where it’s considered a noncriminal traffic violation.

There is even a report by the U.S. Department of Justice called “Loud Car Stereos.” It refers to motor vehicles with amplified audio systems as one of the most common sources of noise complaints.

So yeah, before you crank up that bass, look around for some folks that could get annoyed.

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Most Illegal Car Modifications

The list of illegal car mods is even longer. Everything from upgrading your car’s suspension or exhaust system to enhancements like tinted windshield can get you a traffic ticket if you’re not careful.

Let’s start with the more subtle car mods.

Lighting Mods

When it comes to car modifications, lighting is a popular area for customization. However, most mods are illegal in the U.S. due to safety concerns and regulations. You can get away with mildly tinted headlights or tail lights, but that’s about it.

Headlights

The Federal Motor Vehicle Safety Standards kept us outdated for ages until an infrastructure law was signed a few years ago. Now, we can enjoy factory-installed adaptive driving beam headlights on new cars.

However, if you want to enhance your vehicle’s headlights with LED, for example, the law says NO.

Tail Lights

Things are a lot more simple to understand when it comes to tail lights. You can install aftermarket replacements, which, in my opinion, are very impactful. That’s why I’ve included the “Eagle Eye” tail light upgrade in my Best Tesla Model 3 Mods round-up.

There are two important rules that most states want you to follow:

1. If you install aftermarket replacements, your tail lights must be red or amber.
2. Brake lights can only glow more brightly, and strobe lights are not allowed.

Underlights

Neon lights placed underneath your car are not as trendy anymore. The main reason is the countless expensive tickets Fast & Furious fans received during the last few years.

While a few states allow underlights, they narrow down the choice to amber and white lights. In many states, underlighting is 100% illegal, and in others, you could have neons underneath only on private roads or at car shows.

Not sure why anyone would want neons, but if you do, get a remotely controlled kit.

Light Bars/Rigs

These are favorites of off-road enthusiasts, especially the LED light bars, which are the brightest and most powerful. If you turn on those on public roads, other drivers won’t give you any thumbs up – perhaps some different gestures.

Having light bars installed on a motor vehicle is legal, but each state has its own rules on where and how many you can have. Here is a state-by-state guide if you need more details.

Window Tint

Window tints are the most popular car modifications. Offering comfort and privacy and protecting your interior. Yet, a window tint can also be a safety hazard.

Most states permit a certain level of tint on the rear and side windows, but front-side windows must allow a certain percentage of light to pass through.

The problem is every state has different laws about which windows can be tinted and how much light must go through.

Even if you know what the percentage of window tint in your area is, you may get a fix-it ticket on your next road trip. The same applies to full or partial windshield tints.

So, if you want to go for a very dark tint, check out the window tint laws in the states you plan to visit.

Suspension Upgrades

Everyone who is into automotive customization has thought about adjusting their vehicle height. There are tons of aftermarket products, and these are not considered illegal car mods. In fact, I recently installed a set of Eibach springs on my Model 3.

The Police won’t bother you unless you go too low or too high or you use huge wheel spacers, making your wheels stick out. I couldn’t find a particular federal law addressing ride height or ground clearance, just some FMVSS documents that I barely understand.

What I found was that different states have different rules when it comes to license plate height and headlight height. California, on the other hand, has set a maximum frame height. That said, you should read the requirements of your state.

Aftermarket Exhaust System

Car nuts love loud exhaust systems, especially the old-school muscle car guys. I’m sure you’ve heard the famous saying, “Loud is Proud.” Yet, loud exhausts are some of the most illegal car mods across all states.

Loud Mufflers

Nothing sounds as exciting as a V8 cold start in the morning. I had an SRT Challenger and ran a muscle car blog for a decade, so I know how cool loud exhausts are.

I also know that my neighbors didn’t enjoy it, and so did the cops. They can’t prove that your mufflers are louder than stock, but they’ll still hand you the ticket in most cases.

Straight Pipes

Straight exhaust pipes surely make your engine sound more aggressive and boost performance to a certain extent. While we still see hot rods utilizing such car mods, these are far from being legal.

The absence of emissions equipment violates federal regulations. Cars equipped with straight-pipe exhaust emit more pollutants into the air and can result in hefty fines if caught.

Electric Cutouts

Electric cutouts are the only aftermarket exhaust systems allowing you to enjoy the thunderous sound of your engine only when appropriate. And to get away from the crime scene when it isn’t.

As with all other vehicle modifications on my list, regulations differ from state to state. The most strict rules are in California. You’ve probably heard about the California Air Resources Board studies.

Still, I’ve seen people pass the visual smog check with cutouts in the Golden State.

Engine Modifications

Now, it’s time to talk performance boosters. Both car aficionados and manufacturers are going crazy about horsepower these days. Of course, there are some illegal car modifications that are worth mentioning.

Long Tube Headers

Installing aftermarket headers is fine. In most cases, such car modification won’t break your city rules for engine noise. But long tube headers also affect the engine and tamper the emissions.

Yes, you'll improve your vehicle's performance, but most probably fail on the smog test.

If you know a good tuner who can install the long tube headers without getting rid of the catalytic converter and O2 sensors, you’ll be fine.

Cold Air Intake

Cold air intake systems are car modifications that give your engine more go and better MPG. I say great, but most state regulators disagree as it affects factory emission levels. Hence, in their eyes, such aftermarket parts are illegal.

The good news is you can install a cold air intake and enjoy the benefits of this car modification without worrying about the law. Buy a high-quality unit, and the manufacturer will provide you with a CARB Executive Order (EO) number.

Nitrous Oxide Systems

Spraying your car with NOS on the race track is fine on everyone’s watch. The majority of drag racers rely on power adders these days. But having a bottle hooked up in a street car is just not right, and it’s illegal.

Rolling Coal

Some folks think that burning more fuel in a diesel truck to make it smoke like a train from a Western movie is fun.

What’s the point of using more fuel and shortening your engine’s life without gaining extra power?

I don’t mean to offend anyone, but in my opinion, rolling coal is the most ridiculous thing the car/truck culture has ever seen.

It makes pollution worse and causes road accidents. It violates the Clean Air Act, which makes it illegal, but many are still doing it. I hope EPA will push hard enough to stop this thing across the country.

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My Thoughts on Illegal Car Accessories & Mods

Frequently Asked Questions

As always, I’ll wrap it up by summarizing the article with some FAQs. If you need some essential tips on how to customize your car, check out this article. Thanks for visiting my blog.

What is an Illegal Car Modification?

An illegal car modification is any change or addition made to a vehicle that violates the laws and regulations governing vehicle specifications and equipment.

These modifications may include changes to the engine, exhaust system, lighting, suspension, brakes, tires, and other components.

What Car Accessories Are Not Legal?

Car accessories such as laser jammers, automatic plate covers, flashing lights, and loud car stereo systems are not legal in most states.

It is important to note that what is considered an illegal car accessory can vary from state to state, so it’s best to research the laws and regulations in your area.

Are Car Mods Illegal in the US?

Not all car mods are illegal in the US. Many aren’t banned by federal law. Only modifications violating the rules and regulations in a particular state or region are considered illegal.

For more clarity, get familiar with the requirements set by the Federal Motor Vehicle Safety Standards, the Environmental Protection Agency, and the Clean Air Act.

What Car Modifications Are Legal in the US?

All car modifications that don’t violate state or federal laws and regulations are legal in the US. Here are some common examples:

• Aftermarket wheels
• Aftermarket brakes
• Body kits, spoilers, and lips
• Custom paint jobs
• Mild suspension upgrades
• Mods compliant with emission standards

Is it Illegal to Mod Your Engine?

It is not inherently illegal to modify your engine in the US. However, certain engine modifications do violate state or federal laws and regulations.

For example, modifications that increase the emissions of a vehicle beyond the legal limit are not allowed. Some states also have restrictions on the types of engine mods that can be made, such as limits on the size of the engine or the use of certain types of fuel.