A Class 4 MOT is required for most standard vehicles, including cars, smaller vans, and other light vehicles. The test checks key components such as brakes, steering, suspension, tyres, lights, exhaust emissions, and safety features like seat belts and airbags. It ensures that the vehicle complies with safety and environmental standards. Conducted annually for vehicles over three years old, the test focuses on roadworthiness and emission levels, ensuring that vehicles remain safe to operate on the road and meet legal requirements.