New MoT laws are coming into force in May which could leave unsuspecting drivers with a £2,500 fine.
The rules around the tests are about to change with new failure and defect categories being introduced for cars.
These will be labelled 'Dangerous', 'Major' or 'Minor' with any vehicle receiving a danger or major fault automatically failing.
Vehicles with minor faults will still be able to pass the test, with a record of the fault being noted on their certificate.
However, under the previous laws, as long as your car was still deemed roadworthy then you could keep driving it after it failed, providing your MoT was still valid.
But now, as soon as your car fails it could be deemed 'dangerous' and, if driven with that rated, land you with a fine of up to £2,500 and three points on your licence.
So, if you put your car in for an early MOT and it fails then you could face the huge fine even if your old pass certificate hasn't expired.
As soon as the car fails it will be recorded on the national database, regardless of whether it has an MoT which is still in date.
According to the DVLA: "If your vehicle fails the MOT: you'll get a 'refusal of a MOT test certificate' from the test centre.
"It will be recorded in the MOT database. You can take your vehicle away if your MOT certificate is still valid."
The new categories are being introduced on May 20, 2018 as part of a European Union directive, known as the EU Roadworthiness Package.
But according to RAC spokesman Simon Williams the classifications leave the seriousness of car defects open to interpretation by testers, creating “the potential for confusion”.
Mr Williams said: “While on the surface this change, which is part of an EU Directive due to come into force in May, seems like a sensible move we fear many motorists could end up being confused by the new categories which give an indication as to the seriousness of vehicle defects identified in an MOT test.
Cars will also face stricter emissions testing under the new rules, with limits for diesel cars being lowered. Any vehicle with a diesel particulate filter (DPF) will be issued with a major fault if it is found to emit a “visible smoke of any colour”.