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8 Things That Can Make a Car Not Street Legal

All new cars manufactured in the United States or imported from other countries must adhere to every federal and state regulation to be street legal. Every old car modified or upgraded to be roadworthy should not have any changes that can effectively make it illegal on the streets. 

Here are 8 types of things that make a car not street-legal: 

  1. Exterior modifications 
  2. Interior modifications 
  3. No, lapsed or inadequate insurance 
  4. Malfunctioning or broken safety features 
  5. Structural and functional damages 
  6. Higher emissions than the state threshold 
  7. Illegal or incompatible upgrades 
  8. Banned models, variants, or trims 

You may wonder if a drag car is street-legal or what is the street-legal horsepower limit. A common concern is what type of damage can render a vehicle not street-legal. This guide discusses all the requirements for a street-legal vehicle and everything that makes it illegal.


1. Exterior Modifications

Exterior modifications are not necessarily the most significant things that can make a car not street-legal. However, they are the most evident and easy to spot. It’s far more likely for you to get pulled over for exterior modifications than what your car may have under the hood. 

Every exterior component of your car must comply with all relevant federal & state regulations. While federal regulations are fairly standard, state laws vary within a general ambit, with many specific clauses covering both aesthetic and functional modifications being identical. 

Cosmetic upgrades to enhance the aesthetics of your car, such as paint, are not a concern. The problem lies in all aesthetic changes that essentially affect road safety and what the regulatory authorities consider a risk to you, co-passengers, fellow commuters, and pedestrians. 

Window Tint

You cannot tint any car window to the extent that violates the light transmittance and reflectivity percentages per your state regulations. Take the windshield, for example. You can tint only a portion of the windshield in many states without exceeding the reflectivity limit. 

The reflectivity limit is generally a maximum of 20% to 35%. Some states like Illinois, Maine, and South Carolina mandate non-reflective windshield tint. A few states, like New Jersey and New Hampshire, don’t permit cars to have tinted windshields and front windows. 

All states regulate the percentage of the windows you may tint while adhering to the minimum light transmittance requirement, usually a minimum of 30%. Here’s a map showing state-wise window tint percentages. Also, mirrored and metallic windshield tint is strictly regulated. 

Check your local laws before paying for tinting

Exterior Lights

Here are some good-to-know guidelines for exterior lights: 

  • All exterior lights must be sufficient but not excessively bright, and they should be of the approved colors. 
  • Spotlights are not legal in many states. 
  • Several states prohibit HID or high-intensity discharge bulbs such as headlights and taillights.
  • Also, neon lights under the car are illegal.
  • Your car should have white headlights and license plates, amber taillights and turn signals, and red stop lights. 
  • The hazard warning signals may be amber or red, but the side reflectors should be amber and the rear reflectors red. No other color is permitted. The backup lights should be white.

License Plate Frame, Cover, or Shield

You cannot use license plate covers or shields in many states, such as: 

  • California 
  • Kansas 
  • Illinois  
  • Maryland  
  • Massachusetts 
  • Minnesota 
  • New York  
  • Oregon 
  • The District of Columbia 
  • Oklahoma (doesn’t permit either frame or shield for a car’s license plate) 

The license plate should be lucidly visible, and the number must be distinctly eligible in all states. Any kind of radar, jammer, or reflector for lasers to prevent law enforcement agencies and their tools from detecting or reading your license plate is illegal throughout the US. 

Bumpers and Spoilers

One of the few original requirements for street-legal vehicles for passenger cars is a bumper. Your car must have front and rear bumpers around 16 to 20 inches (40.6 to 50.8 cm) above the road surface. You may upgrade your bumpers, and the debated bull bars are still permitted. 

Spoilers are a relatively grey area because these can be distinct and versatile. You may use a rear spoiler as long as it does not obstruct the view of the driver. The spoiler should not cause any windshield obstructions through the in-cabin and the rearview mirrors on the sides. 

Related The Average Cost To Detail a Car or Truck (Partial vs. Full).

2. Interior Modifications

Interior modifications are not as evident as exterior upgrades or visible changes. Many internal modifications may go unnoticed forever, even if they are questionable or irrefutably a breach of law. However, you must steer clear of the following to keep your car street-legal. 

Steering Wheel

The prevailing federal regulations necessitate a circular steering wheel with a minimum 13 inches (33 cm) diameter for passenger cars. Thus, you cannot have a more playful joystick or any unique shape onboard. Also, Tesla’s butterfly steering wheel may not become a reality. 

You can opt for telescoping steering wheels with various integrated features, like scrollers and other options mounted on them. However, all such subtle changes and uniqueness must be within the ambit of the basic regulatory requirement for a car to be street-legal. 

Cold Air Intake

An aftermarket cold air intake engine upgrade isn’t prohibited per any federal regulations, but it could be a problem if you are in California. The CARB, or California Air Resources Board, has stringent standards to ensure emissions compliance, thus discouraging engine tampering. 

According to Vehicle Code Section 27156 (VC 27156), installing a cold air intake system is effectively tampering with the engine, its smog control features, and other attributes that have a direct impact on emissions. However, you may use a CARB-certified cold air intake system. 

Nitrous Oxide

You can load up your car with some nitrous oxide and gallop fast & furious in Germany. In the United States, you may use gas only for off-road driving. In other words, an N2O engine boost will make your car not street-legal in almost all states except for authorized racing. 

However, you can purchase nitrous oxide for medical purposes. Also, you can use N2O for your car, but only if you are driving: 

  • Off-road 
  • On personal property 
  • At a racetrack for practice, sport, or leisure 

Furthermore, such boosts require timely disclosure to auto insurance companies. 

Loud Speakers

You can install speakers with a phenomenal volume capacity and incredible bass, but playing them at maximum settings may get you into trouble with local law enforcement agencies. Most states have laws regulating noise pollution, which are generally stricter for residential areas. 

Speakers with exceptionally loud outputs are not street illegal per se, but using them might be if people complain or you get pulled over. You can always use the finest speakers but at volume and bass levels that do not inconvenience others. Check your local laws for specific decibels. 

3. No, Lapsed, or Inadequate Insurance

New Hampshire does not necessitate car insurance for owners and drivers. Residents may self-certify that they have the financial resources to pay for damages and medical costs. In Virginia, owners and drivers may pay an uninsured fee and not opt for auto insurance. 

All other states require auto insurance with specific clauses for every component of the policy, such as: 

  • Bodily injury liability 
  • Personal injury protection or medical costs 
  • Property damage liability 
  • Coverage for collision 
  • Uninsured and underinsured motorist coverage 

Your car will be street illegal if you don’t have auto insurance, the coverage is inadequate, or the policy has lapsed. Ideally, you should consider comprehensive coverage, depending on the local regulations. Alternatively, choose a car insurance policy that meets the minimums per state law. 

A few states accept proof of financial capability, thus responsibility, if owners or drivers furnish bonds, make cash deposits, or other acceptable contingency funds, as required by the local laws. However, car owners must sustain these options perennially, like auto insurance policies. 

4. Malfunctioning or Broken Safety Features

All modern cars have several safety features, not all of which are obvious from the outside. However, a few ordinary features are quintessential for road safety, such as taillights, stop lights, and reflectors, which are evident to commuters, pedestrians, and law enforcement agencies. 

Any malfunctioning or broken safety feature will make your car not street-legal. Sometimes, it is difficult to know in real time if an essential feature isn’t working, and people only learn when others report the problem. Still, it is necessary to be proactive to avert untoward developments. 

For instance, you may choose aftermarket headlights, taillights, or other components that don’t have the reflective glass type used originally by the car’s manufacturer. You may get pulled over for such a reason, irrespective of whether the fault was inadvertent or intentional. 

5. Structural and Functional Damages

Generally, a car with significant structural or functional damages, or both, is not street-legal. A few components are fundamental to the street legality of on-road vehicles, such as: 

  • Headlights & taillights 
  • Blinkers 
  • Mirrors  
  • License plates 
  • Windshield 
  • Bumper 
  • Hood (in some states) 

Other damages that are potential gray areas in the legal context include issues like: 

  • Leaking transmission fluid or oil 
  • Wobbly tires or deformed wheels  
  • Loose components of the frame 
  • Cracked windows 
  • Broken frame 
  • Bent or misshapen hood 

Your car shouldn’t pose any threat to you or others. 

Driving without mufflers or with damaged exhausts makes cars street illegal in many states. Getting pulled over with such damages after an accident may not necessarily lead to a fine, depending on the circumstances. However, the best practice is to get a damaged car towed. 

A few otherwise harmless features can make your car street illegal if they malfunction or fail, such as windshield wipers and horns. You must have a functioning horn that is audible enough for around 200 feet (61 m) and working windshield wipers regardless of the weather conditions.  

6. Higher Emissions Than the State Threshold

All states have emission standards for passenger cars. California is among the strictest, but EPA regulations are generally well-defined, and you should not alter anything in your car that can lead to higher emissions than your state’s threshold. Here are the EPA’s on-road resources

Removing the muffler from the exhaust system is illegal in most states. Also, upgrading an engine or making any changes under the hood that increases emissions will make your car street illegal. Check everything from any cold air intake upgrade to failing onboard systems. 

7. Illegal or Incompatible Upgrades

One noteworthy incompatible upgrade is the engine and its power. Theoretically and legally, you can get a more powerful engine during an aftermarket upgrade, as long as the extra horsepower and torque do not spike the emissions from your car, or it will not be street legal. 

All passenger cars must abide by the minimum clearance and maximum height regulations. Thus, you should not lower your car’s profile by tweaking the suspensions or tire size. Also, you should check your state laws and local regulations before installing a rig, with or without lights. 

While low clearance is a problem, lifted or raised profile is also not permitted in most states. You cannot install suspension systems or oversized tires that raise the profile of your car. Besides, suspension changes must abide by local laws. Furthermore, studded tires are a concern. 

Studded tires are necessary for snowy terrains. However, they are illegal on non-snowy terrains because studded tires can damage the typical tarmac. Many states have specific conditions and dates for owners to use studded tires, especially in regions that don’t have much snowfall.

Driving this on a public road might not be the best idea

8. Banned Models, Variants, or Trims

Passenger car manufacturers recall specific models due to distinct issues. Also, the various regulatory authorities report probable problems with specific models, variants, or trims. Driving cars that are flagged by the authorities or manufacturers is illegal in all states nationwide. 

It is unlikely anyone will miss out on a recall or outright ban of a particular model, a variant, or specific trim. However, it is wiser to err on the side of caution. Also, quite a few models get and remain banned in the country. Hence, such cars are effectively not street-legal in any state.

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