Drivers of modified diesel cars are being warned against a specific modification that could see them face a fine if caught.

According to an investigation by the Driver Vehicle Standards Agency (DVSA), thousands of motorists across the UK are driving diesel cars that have been modified to remove the pollution exhaust filter - an expensive part to replace, the Express reports.

Removing the filter costs just a couple of hundred pounds and the process is not illegal, however, driving around in a diesel car without a filter is against the law.

Since 2014, 1,800 cars have been found to have had their pollution filters removed. Drivers of diesel cars can be fined up to £1,000 if caught, while van drivers could be made to shell out up to £2,500.

Vehicles manufactured since 2009 must have a diesel particulate filter fitted, however, these can cost up to £1,000 to repair, with many motorists choosing to avoid the cost of repairs when the filter breaks.

Gareth Llewellyn, DVSA chief executive, said: “Vehicles found to have tampered with or missing DPF filters will fail their MOT... DVSA continues to pursue such offences and will take action against any MOT garages found to be conducting illegal modifications.”

Exhaust system upgrades are among the most popular types of car modification, along with upgrading a vehicle’s wheels.

Investing in a snazzy set of alloy wheels can be beneficial in terms of reducing a vehicle’s weight while also enhancing its aesthetic appeal without any of the worry associated with mods like tampering with the exhaust. Shop for alloy wheels online here.