Car manufacturers are legally obliged to test their own vehicles. This is to ensure they are safe for consumers to drive, but it also allows them to advertise a model’s performance. Key USPs like the car’s top speed, horsepower and mpg are all calculated during the testing phase.

Road safety tests, including car safety crash tests and other kinds of car safety test, are carried out to ensure that cars can operate evenly and safely across the board. During these, cars are tested in a variety of environments, conditions, and speeds.

Below, we discuss the ins-and-outs of a car safety test.

Car testing: what does the law say?

Under UK law, cars must be safe to drive on the roads and any safety issues are wholly unacceptable. If faults are found, then car manufacturers must enact a mass recall on all models. However, testing isn’t just about safety; it’s also about quality.

Under the Consumer Rights Act, all drivers have the right to return their new vehicle after 30 days. As such, fuelled by competition, car manufacturers spend a significant amount of resources quality testing their vehicles.

To learn more about your rights, read our detailed blog on the subject: How to stay protected when buying a car.

By 2022, the UK will need to meet a new set of standards, including the testing and incorporation of new technology such as intelligent speed assistance (ISA), advanced emergency braking (ESA) and lane-keeping technology.

How are cars tested?

Generally, a car safety test is a long and intensive process for car manufacturers. Testing is undertaken in a variety of landscapes, including on-track, off-road and other real-world environments.

However, what does this “testing” entail? Overall, there are many types of vehicle testing, but the best cars for crash safety will have undergone the main bulk of it is as follows:

Crash testing

Everyone knows about the car safety crash test. From the distinct dummy to striking images of the testing process, the test provides peace of mind that the majority of cars are as safe as they possibly can be. However, what is involved in the crash testing process?

To test, car crash testers first drain the car of fuel and replace it with a specialised solution. A variety of collisions then occur from the front and side, which damages the car’s chassis. They then assess this damage, the damage to the dummy and other minute details to analyse the car’s safety. For example, spillage of the specialised solution is noted and measured to test the probability of the car catching fire during a crash.

All cars must meet a high baseline of safety, but some cars are earmarked as being safer than others, which is reflected in the car’s description.

While depictions of this test are quite graphic, they should provide peace of mind. Any modern car you drive has been tested thoroughly and car safety standards and technology are improving every year.

Depending on the results of these tests, cars will receive ratings of various levels. You can learn more about these ratings, here: Car safety ratings explained.

Brake testing

Brakes are, obviously, very important in the running of the car. Due to their importance, car manufacturers test them to ensure they last for a significant period. The reasons for this are two-fold: to maintain safety and to decrease maintenance costs.

Braking is tested through a specialised device known as a brake tester. To use it, a vehicle is driven onto the tester in line with a set of rollers. The rollers are then switched on, which cause the tyres to run. The operator of the vehicle then hits the brakes, which creates a force. This force is recorded by measuring the deceleration of the tyres.

After a matrix of recordings has been noted down, testers can then accurately assess how long the brakes will last, as well their metrics.

Vibration testing

The vibration cars endure can lead to long-term damage. As such, vehicles must be tested to ascertain the effects vibration has on them.

This area of testing is very sophisticated, with each part of the car needing slightly different techniques to test vibrations on. Currently, waveform replication is used most.

Waveform replication is used in each area of the car to simulate vibration, allowing for data to be recorded on the nature of the vibration. This is done at different speeds and durations that mimic real-world driving, allowing testers to conclude whether the car can cope with the physical demands of driving.

How are cars tested for performance?

As well as testing for safety, cars need to be tested for performance before they can be sent out onto the road, including horsepower and emissions.


When testing cars for their performance level, it’s important to make sure the horsepower is right. Horsepower is the unit that measures the power output of engines, and is most commonly tested in a dyno (dynamometer) test.

A dyno test measures engine force, torque, and horsepower. The vehicle is anchored to the floor, and the wheels placed on rollers. The test itself only measures torque and rotations per minute (RPM), which can be multiplied together and then divided by 5,252 to find the vehicle’s horsepower.


Vehicles need to be tested for their emissions to ensure they meet air quality standards. Since 2017, this form of test has been the Worldwide harmonised Light Diesel Test (WLDT).

During this test, the vehicle is driven along a set route that includes both high and low altitudes, multiple temperatures, uphill and downhill driving, and more variables to satisfy that the engine has been engaged in every possible way.

A portable emissions measurement system (PEMS) device is fitted to the exhaust before the test, and as it’s driven, the car’s emissions are measured.

Discover reliable used cars today

The best cars for crash safety are those that undergo thorough testing by the manufacturer so they can last a long time.

Discover a range of reliable used cars from’s network of experienced dealers today.

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