I've got a better idea - with the added bonus of screwing William Hague and his wife and all those other Range Rover drivers, who are probably Tories anyway. Increase the road fund tax on all those "off-road" vehicles which are on road, on our roads, that is - those clunky, chunky, I'm-bigger- than-you types which give a rolling two-fingered salute to the environment, let alone the rest of us road users.
What kind of statement are the people who buy them making about themselves and the way they see the world? Note, first, their infantile desire to be a little higher ... tall man in the saddle indeed. (Except, with Range Rovers, it is often women saying mine's bigger than yours and for some reason they always seem to be wearing green headscarves.) To get ahead, it seems, get an ORV.
Next comes the desire to be different - but in a highly conformist way. Their drivers all want to encase themselves in the same kind of chunky box, different in the same way from the smaller, more streamlined and less polluting cars the rest of us drive.
The Range Rover is a typical spewer forth. It started the off-road car trend back in the 1970s. According to manufacturers' figures, the latest best selling version of this two-tonne monster consumes two and a quarter times more petrol than the 1.6 litre "entry level" Ford Mondeo, the archetypal family car. It produces two and quarter times as much greenhouse gas. Both vehicles carry no more than five adults.
Granted, that as the market for these planet-trashers has blossomed, smaller, cheaper off-roaders have been produced. The three top-selling models in Britain, the Land Rover Discovery, the Vauxhall Frontera and the Toyota RAV4, all cost around half the price of the Range Rover and have considerably smaller engines. None the less, the inherent brutality and inelegance of their design compels them to swallow a great deal more petrol or diesel than the average car - and therefore pump out at least a third more greenhouse gas in going from A to B.
Points A and B turn out to be within the suburbs or inner cities. How strange that these vehicles, made for going up hill and down dale in the great outdoors, are most often seen going backwards and forwards to school, office or Asda.
They are marketed as cars for people who love getting close to wild nature, yet in purchasing them their proud owners demonstrate that they don't give a hoot about the environment we all share. As for those ORV drivers who insist on installing bull bars, it only shows that they're not too fussed about maiming or killing their fellow human beings either.
There is, of course, no such thing as an environment-friendly car. ORVs offend not absolutely but by degree. And yet there is something extra unpleasant about the Explorer, the Terrano, the Grand Cherokee, and their ilk. It's connected with their sheer bulk, their harsh shapes and that daft statement their owners are making. A Jaguar or a Porsche are altogether politer, quieter, more slippery way of showing you have high status and low concern for the environment.
So many off-road cars have now been sold that the average focus group in a key marginal constituency probably contains at least one owner - which gives them pulling power with politicians and all those who rely on marketing data to make up their minds. It is up to the rest of us, no cars or low cars, to take the initiative. People who buy these egregious tanks undoubtedly lack in the sensitivity department. But if we radiate enough shame and scorn, if we sneer at and shun them, they might just start to get the message.