Drivers warned that emission limits “grey area” could result in more prosecutions
JOHN EVANS
A workshop being found guilty of carrying out illegal alterations to a car has exposed a grey area in the law that puts anyone who modifies a car at risk of prosecution, another tuning specialist has warned.
In November last year, Wakefield-based AET Motorsport was ordered by a court to pay £7234 in fines and costs after the Driver and Vehicle Standards Agency found it had made alterations to a car to remove its catalytic converter and modified its engine control unit to increase noise levels, making it illegal to drive on a public road.
Magistrates told AET Motorsport that the case was rightly brought by the DVSA and that business owners were obliged to know the law.
However, James Wills, director of Newton Abbot-based Auto Dynamix, has claimed that while the court’s judgement was right, the case has exposed contradictions in the law concerning exhaust emissions that he believes need clearing up.
“A de-cat exhaust system on a road-going car is illegal and will cause a car to fail its MOT,” he said. “So to achieve near enough the same performance results, drivers are having sport catalytic converter systems fitted to their cars instead. These are sufficient to get the car through the MOT, but I doubt they satisfy the emissions limits set at the car’s type approval stage.”
To enable better gas flow, a sport exhaust may contain less than half the catalyst material of the car’s standard system or, in the case of a car with multiple catalytic converters, considerably less than that. However, so long as it’s an EC-marked system and the car’s emissions are within limits at the required low engine speeds when there’s also no load on the engine, a vehicle fitted with an approved sport cat (ideally supported by modified engine management software) will satisfy the MOT regulations.
The problem arises when, away from the MOT test centre, with the engine running at higher speeds and with a turbocharger boosting, it is likely to produce emissions that exceed the type approval limits specified for the vehicle when it was certified with its standard cat exhaust system.
“For this reason, I’m concerned that were an inspector to properly test the emissions of a car fitted with a sport cat across its operating range, they would find it illegal,” Wills told Autocar. “This contradiction between MOT and vehicle type approval regulations needs to be sorted out before s
