Emissions crackdown will target modified cars

The Department of Transport says it wants to improve air quality. Guess what it thinks of your aftermarket exhaust?

By PH Staff / Tuesday, 1 September 2026 / Loading comments

Vehicle emissions, we can all agree, are something of a nuisance. What a wonderful world it would be if a large petrol engine, in the course of its lively combustion process, emitted nothing more consequential than a pleasing fragrance? Of course, were that the case, the UK Government would still find something to complain about (taxing our vices is the one thing it is exceptionally good at), but it would at least it would provide the powers-that-be with a less ample area of research, and fewer opportunities to financially bonk people over the head.

Its latest wheeze, which it has been building up to for some time, is a proposal to ‘ensure that road vehicles continue to meet the same legal emissions requirements that applied when they were built and first registered for use on the road’. Its reasoning is that road transport is the largest single source of nitrogen oxides and the second largest source of atmospheric fine particles in the country, and that the current rules are not up to snuff when it comes to the job of ‘properly controlling’ such emissions once a car has left the factory.

Forget that nitrogen oxide emissions are around 80 per cent lower than in 1990 (thanks in small part to the escalating Euro standards introduced in 1992), and the nation’s largest source of fine particulate pollution are wood-burning stoves (a much more problematic area to legislate). The Government’s suspicion that this is costing the NHS billions - a problem that it somehow thinks will not be suitably alleviated by the 2035 phase-out of all combustion engines - is basically assumed to be irrefutable.

Accordingly, where there is essentially ‘no requirement to maintain the functioning of the ECS of Euro 5 or 6 light-duty vehicles or Euro VI heavy-duty vehicles’ currently, the Department of Transport reckons there ought to be some, as there was for earlier Euro standards. And especially since its research suggested that around two-thirds of more recent diesel cars were emitting more than 3 times the level permitted, and fewer than 1 in 10 passenger vehicles 'met the official limits for nitrogen oxides’ overall.

There are several moving parts to this, although from where PH sits, the sheer volume of that alleged rule-breaking suggests this has less to do with a minority consciously removing catalytic converters or particulate filters, and more to do with the failure of OEMs to develop so-called emissions control systems (ECS) that continue to work effectively beyond the type approval process. But as you might expect, the Department of Transport is less willing to fry that fish than it is to pounce on owners for shoddy maintenance. Or else modifications.

Thus drivers will be exempted from a situation where ‘the reason for the vehicle having excess emissions is something outside the control of the owner/user’ - i.e. if your car isn’t functioning within the permissible limits, but everything is present and correct and appropriately serviced, you’re home free (or rather in a no-fault grey area where blame does not fall on you or the OEM). For everyone else not off-roading (read: farmers), the Department of Transport proposes that the law will be as blind as Louis Braille - i.e. it will not distinguish between excess emissions caused by lack of upkeep and those triggered by ‘hardware or software’ alterations.

Ostensibly, this is to help simplify enforcement (and doubtless increase the chances of a successful prosecution) rather than clamp down on those of us who like to tinker; in fact, the open consultation document is adamant that ‘vehicle alteration is a legitimate practice’, and that the Government is not seeking to ‘prohibit all vehicle modifications’. Nevertheless, in practice, it suggests that from now on, the legality of any alteration will depend primarily on how it affects the pertinent new-build emission limit - and tellingly, it will not matter whether that effect was intended or not.

So while it makes clear that the four illegal horseman of its proposed apocalypse would be a) the removal or ‘deletion’ of particulate filters, b) the removal of catalytic converters and associated sensors, c) the manipulation of selective catalyst reduction systems (i.e. AdBlue), and d) the manipulation of exhaust gas recirculation systems - in other words, the Fab Four of many an oil burner workaround - it will not ultimately distinguish between any of them and an otherwise innocent tickle of a petrol engine ECU, if the latter results in the same red flag at the tailpipe.

Is that fair? Well, the purpose of the consultation, as ever, is to gather as many alternative viewpoints as possible. As you might expect, the Performance Automotive Aftermarket Association has some - not least a wariness of the black and white position a politician might choose to adopt on the subject. Which is understandable given the can of worms the Department of Transport intends to kick over for the thriving businesses it represents, not to mention the number of customers who might find themselves in the crosshairs just six months after the legislation is implemented. This, we’re told, is pencilled in for summer 2027 - but you only have till midnight on September 6th (this Sunday) to make your voice heard on the subject. We heartily recommend you go here and do just that.