From May this year the MOT is changing, with new defect and failure categories coming into force. These will classify faults on cars going through the test on their severity.

You will see three grades of faults – Dangerous, Major and Minor. You can think of Minors as being like an advisory but Major and Dangerous faults will see your car fail.

The RAC believe that this is potentially putting road users at risk as the individual tester will have to use their own judgement to decide what grade a car receives.

Simon Williams, an RAC spokesman said: “Rather than MOT failures simply being black and white, the new system creates the potential for confusion as testers will have to make a judgement as to whether faults are ‘Dangerous’, ‘Major’ or ‘Minor’. This will surely be open to interpretation which may lead to greater inconsistency from one test centre to another.”

The RAC is also concerned motorists may struggle to understand how Dangerous and Major problems differ.

Under the new rules, faults that are deemed Major will need to be fixed and the car re-tested. If a fault is deemed to be Dangerous, it will lead to failure of the test and make the car illegal to drive on the roads.

Earlier this year, in January 2018, the government decided not to extend the time before a car’s first MOT to 4 years.

While cars are getting more reliable, and the RAC’s own data says it would be OK for most cars to be tested after 4, rather than 3 years, it still believes it would be a bad move. High mileage cars need to be tested sooner as 4 years would be too long.

Staying with the current three year rule will “keep it simple”, which most road users will be pleased about.

The new MOT rules have some other changes, the biggest coming for diesels. It surrounds the DPF filter (diesel particulate filter) – if one is fitted to a car and it pumps out smoke, of any colour, it will be classed as a Major fault and, as above, will fail the MOT.

Another significant point is for cars with tampered with or disconnected DPF’s. Without the car owner giving them a ‘legitimate’ reason the MOT tester will have to refuse the test.

More stringent checks will be carried out on three specific areas of vehicles that can potentially lead to a serious accident.

Steering systems, blown reversing lights and “significantly or obviously worn” brake discs.