The Independent Automotive Aftermarket Federation (IAAF) has published a new White Paper connecting its campaign for a statutory £54.85 minimum MOT fee directly to unlocking Particulate Number (PN) and NOx emissions testing in Great Britain.

The report, titled Squaring the Circle: Mandatory PN Testing in the EU Roadworthiness Regime, the UK MOT Position, and How a Minimum MOT Fee Could Unlock UK Adoption, argues that Department for Transport (DfT) hesitation around PN testing stems from implementation costs rather than technological viability.

By fixing a statutory minimum MOT fee at the current £54.85 cap, the IAAF says government can eliminate loss-leading £20 to £30 tests without increasing costs for motorists. This guaranteed return would give testing stations the financial confidence to invest in specialised PN counters and NOx measuring equipment.

Mark Field, Chief Executive of the IAAF, stressed that locking in the existing maximum fee resolves the funding bottleneck for advanced emissions equipment.

“Inflation alone would justify an MOT fee of around £95 today. We are not asking for that,” said Mark.

“We are asking for a floor at the price that has already been frozen since 2010, so that the garages carrying out these tests properly can afford the equipment they need.

“This isn’t about increasing costs for motorists; it’s about removing the only reason government itself has consistently given for delaying implementation.”

Modernising the diesel MOT inspection

The White Paper highlights critical shortcomings in the existing diesel MOT routine.

Traditional smoke opacity meters and visual checks routinely fail to catch software-based Diesel Particulate Filter (DPF) deletes or gutted housings that retain their external appearance.

IAAF research indicates a vehicle with a compromised or tampered DPF can emit particulate pollution equivalent to 10 to 20 compliant Euro 6 vehicles, with PN testing representing the only reliable diagnostic method to identify these failures during a routine inspection.

The federation also pointed to policy inconsistencies, contrasting Clean Air Zones and London’s ULEZ, where non-compliant drivers face daily charges of £12.50, with an MOT test regime that allows high-emitting tampered diesels to pass undetected.

“The evidence is settled and the public health case has already been made,” said Mark. “The only remaining barrier is funding.

“A statutory minimum MOT fee removes that obstacle without increasing the maximum price motorists pay, while giving garages the confidence to invest and helping government deliver cleaner air without further delay.”