When we think of modified cars, most of us will have some preconceptions.
We’d dare say some of you are picturing a group of 18 year old lads hanging out in a car park, doing donuts at 2 in the morning in their slammed hot hatches – before driving off to bother the staff at a 24 hour McDonald’s.
But aftermarket modifications aren’t always so garish, so loud – or so aimed at the spotty.
And they’re not all just for show either. Alloy wheels, exhaust filters, lights – they can all affect functionality, and influence the outcome of an MOT test. Understanding how modifications you make to your car may impact the testing process is important for everyone. So, let’s delve into the world of modified cars and the potential impact on your MOT test.
Note – some of these can impact your insurance, too.
Body and lighting mods
Altering the exterior of a vehicle – by adding body kits or custom paintwork – is generally acceptable and won’t affect your MOT. but you need to make sure these modifications don’t compromise the structure of the car, impact safety features in any way, or cause rubbing or seizing of parts.
Using non-standard headlights, tinted lights or non-UK aftermarket light clusters may affect visibility or potentially dazzle oncoming drivers. The UK has very strict regulations on the colour temperature and light type used in headlights, which can lead to MOT failures if not met.
Rear lighting must be intelligible and all signalling (indicators, brakes) must be in working pairs. Reflectors, fog lights and a rear licence plate lamp must also be present.
Read more about vehicle lighting requirements.
Performance mods
Engine tuning and swaps
Engine tuning is common among car enthusiasts, but modifications that affect emissions or that exceed legal limits may lead to MOT failure. They’ll also impact efficiency, if you care about that sort of thing!
Swapping engines must adhere to regulations, so that safety and emission standards are met – and of course, should only ever be done by a pro mechanic to ensure a proper fit.
Aftermarket (read loud) exhaust systems are a common modification. However, they must meet noise and emission standards – and if they don’t, you could be facing an MOT failure. Lowering or raising the suspension is another common mod, but this can impact handling and stability greatly – particularly in cars not designed to be lowered. To make sure these modifications are legal, consult a professional mechanic for guidance.
New alloy wheels
After a lifetime of scraping into kerbs, swapping your shredded alloy wheels for some shiny new ones is a popular upgrade. But not all wheels will fit correctly – and some can impact the vehicle’s handling. The overall sizing of wheels and tyres is also a major issue, especially considering that it can impact speedometer and odometer accuracy. Always make sure your alloys and tyres are suitable, and talk to a professional if in doubt.
Braking system upgrades
Installing high performance brakes is acceptable, as long as they enhance safety.
Interior mods
There are only so many rules around interior mods, mostly concerned with visibility, distractions and seatbelts.
Lots of people like to upgrade their seats to comfier (or sportier) varieties. As long as the seats and seatbelts meet safety standards, this is fine – but improper installations may lead to MOT failure, so get them done by a qualified mechanic.
Replacing the steering wheel is allowed, too – but modifications shouldn’t get in the way of safe driving.
Flashing, bright, blue or purple interior lights are not allowed at all and can result in police intervention on the road – as can an infotainment system that leans more on the entertainment side than it does information!
Mods made before the MOT test
If you’ve modded your car and are yet to have an MOT, it’s a good idea to consult with professionals who specialise in vehicle modifications. They can tell you whether your modifications are okay, and what adjustments you might need to make to pass the MOT test.
Book your MOT now
Book your MOT test in Eastleigh today, with We Only Do MOTs. We promise to provide an impartial, independent MOT to everyone – and will carry out most minor repairs for free.Send your message to enquiries@onlydomots.co.uk or call us on 023 8064 7180
