11 Common Illegal Car Modifications

Illegal Cars

Most vehicles are a compromise designed to appeal to the widest variety of auto buyers. It’s no wonder then that factory stock trucks aren’t brilliant off-roaders and cars have sometimes huge fender gaps. Owners perform modifications to get the vehicle more in line with their ideal vehicle, but sometimes the mods are beyond what the law allows. Here are the ten most common illegal modifications.


Radar Detectors

Most states only prohibit use of radar detectors by commercial vehicles. This means every single trucker you’ve ever seen is running illegally, as they most likely have a quality radar detector in the cab. Other states have odd laws that allow radar detectors, but do not allow you to mount it in the windshield area, as it might obstruct your view of the road. So, it’s legal, but you could still get a ticket. Much like Oklahoma for example, where radar detectors are allowed, but use of one is a traffic violation. Go figure.


Loud Exhaust

Your sweet ‘70s muscle car with the naked lady mud flaps doesn’t need those cherry bombs, and it certainly doesn’t need to be that absurdly loud. An exhaust system can flow extremely well without creating a ton of noise, annoying your neighbors, or attracting local law enforcement. Most cities have a vaguely worded ban on increasing the noise level, and while the cop has no way to prove it’s louder than stock, you’re still getting a ticket. So it’s important to know your local regulations on this. In Kansas for example, state law requires a muffler to be less than 90 decibels when measured from a distance of 50 feet.


Bro Trucks

Trucks have a higher ground clearance than cars, as they are meant to be used for work, and can even see light off-road duty. Some enthusiasts take it a whole lot further and install lift kits. A 4 inch lift usually looks pretty good and offers a nice increase in ground clearance. The monster trucks that are 2 or 3 feet higher than stock tend to handle like a refrigerator on ice skates and can be a danger to the driver and other motorists. Lift laws vary state by state, with some having maximum limits on bumper/light/reflector height. A few states have no limits, but if you’re sitting eye to eye with the dude in the Kenworth, it’s probably illegal.



Like lifted trucks, low riders are subjected to various state laws regarding vehicle height. However, due to a history unfairly tied to gang activity, low riders get more attention from police than even Bigfoot or Grave Digger. If a car is too low, and scrapes, it can be deemed an unsafe vehicle, and ticketed or even impounded. Fortunately, hydraulics were invented as a means around these laws, but most cities prohibit the use of hydraulics while moving, others ban them above 15 mph.


Under Body Neons

Laws prohibiting additional lighting on your ride are meant to prevent losers that would pretend to be police. If you read the specific laws, they usually ban flashing or rotating blue and red lighting, and spotlights. Some areas have vague laws, and the local city revenue generation squads do their best to find anything to cite. Underbody neon kits were popular at the turn of the century, but recently the trend has faded. While driving with them on can look pretty cool if done right, it’s a sure way to get an expensive ticket.


Emissions Removed

Back in the ‘70s, you could remove the emissions equipment from a smog choked car, do a little carb tuning, and it wasn’t unbelievable to see a gain of 30 or 40 horsepower. 40+ years later, it’s not the ‘70s anymore. Modern fuel injection combined with dozens of computers and sometimes hundreds of sensors make for an engine that can be powerful and meet emissions standards (yes even California). All of the Big Three have recently built supercars with a minimum of 650 horsepower, while meeting EPA regs. Stop unbolting stuff you need.


Headlights/Taillights Modified

Altezza tail lights were one of the first noticeably visible tuner mods, debuting on the 1998 Lexus IS, and shortly thereafter, every single Honda Civic in the high school parking lot. The clear and chrome housings looked startlingly different, but early models didn’t bother looking into DoT certification. The same thing happened with headlights, with varying levels of chrome, black paint, or fake carbon fiber. The dollar store build quality led to many of them leaking or fogging, and a strict safety inspector will call you out on them.


Super Dark Tint

This one is confusing, as tint laws vary from state to state. It’s not just the tint percentage (a measurement of how much light can filter through the tint), but what windows can be covered. Unfortunately, it seems to be selectively enforced, as a 5% limo tint is ignored by LEOs in some areas, but get a fix-it ticket in the town next door. Best bet is to just ask a reputable tint shop about the local laws. Some shops won’t even install illegal tint.


Plate Frames

Seriously. Who would have thought that those cheesy bling plate covers would be illegal? Unfortunately, all the plastic crap sold in auto parts stores isn’t illegal, so someone is still going to dress up their ’87 Ford Festiva. Before they do, let them know that any plate frame that covers any part of the numbers, letters, or state name is illegal and can receive a ticket.



Okay, sure, there’s not a single nitrous manufacturer on Earth that claims it’s legal to have a bottle hooked up for use on the street. Still, probably 95% of the time a street car receives a nitrous injection kit, it isn’t used just on the track. Sometimes it doesn’t ever see the track. The reason for its illegality is the unknown danger first responders would face in an accident. That high pressure nitrous bottle in the back of your Pinto that just puked its gas tank onto the highway, well, that’s a dangerous situation, and anything that makes firemen nervous should be banned on the street.


Rolling Coal

If you want to spend a lot of money to burn more fuel without the side effect of horsepower, buy a Harley. If you want to spend a bit less, but up the dumb factor, then rolling coal is your thing. Yes, people spent time and money altering their diesel trucks to burn far more fuel than necessary, just to make smoke pour out the exhaust like a 100 year old train. Oh, there’s also the extra wear it causes, leading to a shorter engine life, and the loss of power. Yes, they pay extra to waste more fuel and go slower. New Jersey, Illinois, and Texas, among others, are working on legislation to make this a serious fine, in some cases as much as $5,000.  Hey, like John Wayne said, “If you’re gonna be dumb, you gotta be tough rich.”

These are the most common illegal vehicle modifications, but let us know if you’ve been cited for a mod not on this list.

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