Treat 4x4 as trucks
ok - So there are legitimate uses for 4x4's. Farmers etc etc.
They can't be registered at a metropolitan address.
They have a reduced speed limit as per trucks.
The police enforce this.
These allow people who genuinely have a need for them to drive them, but severely inconvenience the Porsche Cayenne owners out there!
You'd have to think about how you apply this - Maybe on a Kerb Weight basis? Over 2 tonnes and up you go? That would catch Rolls' as well, so there would have to be other criteria, such as being 4WD. That would also exclude the "light 4x4's" like the RAV4 and Subaru's, which is fine from my perspective.
That'll take a few of those Chelsea tractors off the road.