Overloading a car: impact, penalties and safety guide

2nd Apr 2025

Overloading happens when a car carries more weight than it's designed to support. That's why it's important to be aware of your vehicle's weight limit, otherwise you risk damaging your car and breaking the law.

All vehicles have a weight limit and it's easy to overload a car if you are carrying lots of people and luggage.

In this know how guide, we explain how overloading a vehicle happens, what impact it has on your car and the penalties you may face.

If you are looking for guidance on roof racks, read our guide to car roof weight limits.

What is vehicle overloading?

Overloading a vehicle happens when a car or van bears more weight than it is designed to carry. All vehicles have weight limits and it's important to understand these and never exceed them.

Your car's weight limit is usually detailed on a sticker or plate on the vehicle itself (usually inside the driver's doorframe). The weight limit will also be listed in the owner's manual for the car or van.

Impact of overloading a car or van

Overloading can damage your vehicle and make it more difficult to control on the road.

5 things that happen when you overload a vehicle

The vehicle becomes more difficult to control. Your stopping distance increases as the brakes struggle to cope with the extra weight. Acceleration becomes slower as the engine labours to move the vehicle. You may also notice the steering is sluggish and less accurate.
Fuel consumption increases as the engine works harder to move the extra weight. This results in poor fuel efficiency and more trips to the pumps.
Reduced tyre life. Overloading your vehicle puts a lot of stress on your car's tyres, increasing heat and wear. The extra heat and pressure can also increase the risk of a tyre blowout.
Increased wear and tear on suspension and brakes. Your vehicle's components are designed within the parameters of your vehicle's design. If you exceed the weight the vehicle is designed to carry then you will reduce the life of key parts, like the suspension and brakes.
Overloading a vehicle is illegal. It can land you with a fine or even prison if you are found guilty dangerous driving under the Road Traffic Act 1988.

Can overloading damage a vehicle?

Overloading a vehicle can lead to significant damage to a vehicle and to some serious safety risks.

The extra weight can damage essential components like the suspension, tyres, and brakes. It will also overwork the engine, which may result in overheating.

In the most extreme cases, overloading will result in structural damage to the frame of the vehicle.

Additionally, the added weight puts stress on the gears and can reduce vehicle stability, making it harder to control, especially in emergency situations.

Over time, these damages can result in costly repairs and reduced vehicle lifespan.

Instant cover available

24/7 rescue at the roadside
Help to get home if your vehicle can't be fixed
5 Star Defaqto rated cover

Buy now

*Price is based on European comprehensive breakdown cover for a 14 day trip, in a vehicle up to 1 year old, travelling in zone 1.

What is Maximum Authorised Mass (MAM)?

Maximum Authorised Mass (MAM) refers to the maximum weight a vehicle is legally allowed to carry, including its own weight and any load (including passengers).

Also known as Gross Vehicle Weight (GVW) or permissible maximum weight, it’s specified by the manufacturer and ensures the vehicle operates safely without overloading, protecting its components and maintaining road safety.

The MAM or GVW will be listed in the owner’s manual and is normally shown on a plate or sticker fitted to the vehicle (usually inside the door frame).

What is unladen weight?

Unladen weight what a vehicle weighs when it is empty and not carrying any passengers, cargo, or additional equipment (such as bike or roof racks).

It includes the vehicle's standard components, such as the engine, body, and a full fuel tank, but not the load it carries.

This weight is important for determining load capacity and legal limits.

It will also be specified in the car owners’ manual.

Who is responsible for weight limit of your vehicle?

The driver of the car is responsible for ensuring the vehicle is not overloaded. This means the driver must ensure the passengers and any luggage/cargo does not exceed the vehicle's specific weight limit.

When it comes to vans and commercial vehicles, the driver and the employer may be held responsible for overloading and face fines, penalties and criminal charges if an accident occurs.

Penalties for overloading a vehicle

Overloading a vehicle can lead to a variety of consequences, including penalties and legal action.

If a vehicle is found to be overloaded, the Driver and Vehicle Standards Agency (DVSA) can issue a fixed penalty and penalty points.

The fines are structured based on the level of overloading:

£100 for being less than 10% over the weight limit
£200 for being between 10% and 14% overloaded
£300 for exceeding the weight limit by 15% or more

In serious cases, such as overloading by 30% or more, the driver may be issued a court summons, and the most severe consequence could be a two-year prison sentence if found guilty of dangerous driving under the Road Traffic Act 1988.

Additionally, if a vehicle is overloaded, the driver may be prohibited from continuing their journey until the weight is reduced.

Overloading a car or van may also invalidate the vehicle's insurance policy.

Get a service or repair at home

RAC Mobile Mechanics can come to you, saving you the hassle of going to a garage.

Book now

Tips for not overloading your car

Before you set off on your next journey, check out our helpful tips to avoid overloading your car.

These are especially important if you know you’ll have a larger than normal load – whether that is passengers, cargo, or a combination of both. Know your legal limits before getting in the vehicle.

It is important to always check your car owner's manual for its Maximum Authorised Mass (MAM) and total weight capacity, which includes the weight of passengers and cargo.

If you are transporting heavy items, use a scale or research the weight of items you plan to carry.

Once you know this information, distribute the weight evenly throughout the vehicle to prevent uneven strain on the suspension, tyres, and engine.

Also, drivers should regularly check that they are not carrying unnecessary items, especially for longer journeys.

Finally, make sure that you know how roof racks and bike racks will also impact the weight of your vehicle.