No taxes are popular - but some taxes are less unpopular than others. One of these is the company car tax introduced in the April 2002 budget. This provided some financial come-ons for employers and company car drivers to choose their cars on the basis of lower levels of CO₂ emissions, rather than the old system that rested on an ability to milk the system by claiming tax relief for unnecessary business miles. According to an assessment by the Inland Revenue, this has led to quite a dramatic change in buying - and in driving - habits.

In 2002-03 there was a reduction of 400m miles in claimed travel by company car drivers, an improvement that can be expected to continue in later years. Cynics may say that people are not actually driving less, merely claiming less, but the Revenue was presumably trying to take that into account in its figures.

It is not just the Treasury that is happy. So too are the companies that run the cars. For them, savings have come out at £15m a year more than the £20m reduction that the Treasury budgeted for. On top of that, there were estimated savings from 25,000 to 35,000 fewer tonnes of carbon emissions - the equivalent of a reduction of 0.1% in all CO₂ emissions from road transport in the UK. That may sound small, but it is a move in the right direction against a trend that has proved hard to stop and the gains are expected to continue as more firms take the green route and as the new generation of environmentally friendly company cars are sold into the second-hand market. The government has taken a lot of flak from the unpopularity of a number of its high profile policies. Here is an example of a useful policy that is unquestionably working well.