Tenner says they stick a rule in that exempts cars made before current year minus 20, so the classics can do what they want and the modifying scene for anything reasonably new is killed stoned dead. It's big vote winner amongst the middle class mafia and non-petrolheads, getting tough on loud exhausts, body kits, stance, air lift, you name it - because we all know EVERYONE who does that stuff is also speeding, doing burnouts in car parks, selling crack, human trafficking, etc etc etc.....
When we all know the most dangerous drivers all have poverty spec 2 litre diesel BMWs and Audis 😉