How do you save the planet?

The car industry has done its bit by making greener vehicles. Now we have to buy them, says Sean O'Grady

Time for a little analysis, and some soul-searching. The good news, brought to us by the Society of Motor Manufacturers and Traders (SMMT), is that new cars are getting cleaner. As you see from our chart, in 1997 the average carbon dioxide emissions of new cars sold in the UK was 189.8g of CO2 per kilometre travelled. Now, after much effort from the car makers, the figure is down to 167.2g/km, a reduction of 12 per cent or so.

But there's another statistic we need to ponder as well. Today's Ford Focus emits some 26 per cent less CO2 than did its predecessor, the Ford Escort, 10 years ago. If the Escort is anything to go by, then, cars are actually even greener than the emissions figures would suggest. The discrepancy between this much-improved performance by individual models and the much more modest change in the overall market's environmental showing is as a result of the changing mix of cars sold.

The rise of the heavy SUV must have been a bad contributory factor; the increasing number of MPVs another, while the increase in prosperity in Blair's Britain (well, you can't deny it), means that we're generally driving posher brands with bigger engines than we did in the 1990s. Yesterday's 1.6-litre Mondeo has been replaced by today's 2.5-litre BMW 3-Series, shall we say.

Of course it must be admitted that the manufacturers' improved performance - better CO2 numbers and better fuel consumption as well - has come about as a result of ever more stringent official rules and regulations, often imposed in the teeth of the car companies' opposition. The Euro I/II/II/IV series of emissions standards for engines was one big step; the end of leaded petrol another; the standard fitment of catalytic converters yet another. The increasing cost of fuel has also played a part, though this hasn't been quite as dramatic as some of the motoring lobby would have us believe. Increasingly, tax rates and duties are related to engine size or green-ness, which has given the car makers a spur to make their smaller engines still more powerful and fuel efficient.

Still, the boffins and the engineers deserve our thanks for meeting and exceeding those technical standards, even as officialdom and consumers demand still safer cars, which usually means heavier, vehicles. The problem, perhaps, is that we are all buying the wrong types of cars. It doesn't matter if Ford's family saloons are so much more economical and clean than they were if we're off running around in Land Rovers instead. As usual, in other words, the public that condemns "evil" car companies and "cowardly" governments is itself, or elements of it at any rate, the most guilty of all.

The most sobering thought is this. If we had retained the same pattern of car-buying that we had 10 years ago (ie, smaller, lighter hatches and saloons), then we would now be looking at an average CO2 emissions figure for new cars of some 140g/km (by 2008). This just happens to be the EU's voluntary target figure for the car industry. All the wailing and gnashing of Euro-teeth at the failure to meet this target, and all the controversy about replacing it with a still harsher (120g/km by 2012) and compulsory target has to be seen in this context. Tellingly, the French are rather closer to the EU target, because they just don't have the same taste for SUVs as we have on this side of the Channel. I don't want to demonise SUV drivers: they get enough stick already. But it is still the case that they ought to think whether they really do need four-wheel drive and huge ground clearance for the school run.

As it happens, there are many more cleaner and greener offerings than there were even a few years ago. Even in the SUV sector you'll find cars that are (relatively) kind to the planet. You could, say, trade down from a BMW X5 (229g/km of CO2, at best) to a Honda CR-V (177g/km, at best). Some diesel variants of the Ford Fiesta, the Citroën C3 and Fiat Panda all achieve better than that future European benchmark of 120g/km. But if we all go out and buy SUVs then we'll never hit the target, will we?