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Can I Modify My Car And Not Be At-Fault For Accidents in Utah?

Posted January 24, 2023 | Personal Injury Blog

What’s the fun of having a great car if an owner can’t personalize and modify it to its peak? While car enthusiasts constantly search for methods to get the most out of their vehicles, there may be legal ramifications after an accident if a person is not careful.


Laws on Accident Fault in Utah

Utah is one of 33 states with comparative negligence laws applying to auto accidents. After a crash, insurers review the evidence and assign a percentage of responsibility to each party. If a person disagrees with the assessment and settlement offer, that party can take the matter to court to get a more favorable result.

The only individuals who collect their percentage of damages are those who are less than 50% at fault. Parties with more than that level of responsibility for the incident do not have the right to collect compensation.

How Car Mods Can Affect Fault

The pertinent issue with car modifications is whether the conversion contributed any part to the accident. Adjusters or courts consider not only the drivers’ actions but also the road’s condition, the state of the vehicles and other factors surrounding the crash.

For example, if one of the drivers has an illegal car modification, the vehicle might not be street-legal. The driver’s liability will likely rise. Any modification, legal or not, that interferes with the safe operation of the vehicle typically increases the level of fault for whoever is responsible for the alteration, which may or may not be the driver of the modded car.

The Responsibility for Modifications

The actions of the driver of the modded car affect whether the individual bears any fault or maintains coverage from the insurance agency. One crucial factor is if the driver alerted the insurance company to the existence of any modifications.

Mods often change the value of the car and how the vehicle operates. Insurance firms calculate the cost of premiums based on a vehicle’s risk, and changes to the automobile can significantly alter that risk. An application for car insurance usually asks if a car has any modifications. If the owner does not answer honestly, the person may forfeit coverage.

Another vital consideration is who did the work on the car. If the owner does the modification and the result is an unsafe or illegal vehicle, the owner bears fault for those conditions. This fact can hold true if the owner has an acquaintance do unauthorized mechanic work.

However, suppose the owner takes the automobile to an authorized mechanic who does shoddy work and does not install the modifications correctly. In that case, the technician may bear some blame. Mechanics have a duty of care to customers and must provide safe service.

If the modification is legal but a defective part instigated the accident, the part manufacturer may be to blame and bear some of the fault. This situation would involve a product liability claim.

Legal and Illegal Car Modifications

Whenever a car owner wants to make a modification, the person should ensure that the vehicle remains street-legal after the adjustment if desiring to drive it on public roads. Each state has different requirements for street-legal cars.

Modifications fall under three categories: aesthetic, functional and performance. In other words, mods add features to either enhance the car’s looks, luxuries or driving ability. The following information discusses some of the current regulations in Utah.


A vehicle may have two spotlights, and the Utah Code does not comment on under-glow neon lights. However, only authorized vehicles may have rotating lights. Blue or red lights that flash or rotate are only permissible on law enforcement vehicles.


Counties vary on noise ordinances that affect how loud a person can play a sound system. All automobiles must have a muffler to prevent excessive vehicle noise. A car owner cannot alter the engine’s sound with a muffler that has a cutout, bypass or some other device.


Most states have regulations against aftermarket tint. Rear and back side windows may have any shade of darkness, but a rear window tint requires having side mirrors. Front windows must allow at least 43% of light to shine through. A person may put a non-reflective tint above the AS-1 line on the front windshield. No kind of reflective tint is legal.

Vehicle Dimensions

In Utah, a vehicle may not reach over 14 feet high. Frame height depends on the gross vehicle weight rating. A car may be no longer than 45 feet and no wider than 102 inches. The base of the vehicle floor cannot rise over three inches above the topmost part of the frame.


A vehicle owner has the freedom to alter and modify an engine as the Utah Code lists no specific restrictions. However, Davis, Salt Lake and Weber counties have emissions tests. If the vehicle does not pass because of modifications, the car will not be street-legal.

Such statutes are liable to change, so a vehicle owner needs to review the current laws to ensure any modifications are legal.

Other Thoughts To Keep in Mind

While people have substantial freedom to modify their vehicles, they must remember that some people may carry biases against modified cars. Regardless of what a vehicle has under the hood, a witness or adjuster may presume a sports car was speeding or driving recklessly after an accident.

A vehicle with very bright lights or that pushes the limits of permissible noise levels may lead an officer or bystander to assume that the driver of the modified automobile was being irresponsible. Even if the mods are legal, anything that contributes to distracting another driver or reducing visibility can be reasons for someone to assume the modded car has more significant fault in the accident.

Legal Assistance for Drivers of Modded Cars After an Accident

Car mods can be an exciting way to express oneself, but vehicle owners should consider the consequences of such adjustments and ensure any changes to a vehicle allow safe operation. Car modifiers must also prepare for the bias that may come with such a vehicle, especially after an accident. If you need a contemporary lawyer who understands and can provide solid guidance, call or message Fielding Law for a free consultation.

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Text edited by Mitchell Fielding, a personal injury lawyer and partner at Fielding Law. Mitchell is known for his hard work ethic, friendly personality and dedication to the law. You can find out personal injury law offices in Taylorsville, UT and Mesquite, TX.