Drivers have been urged to switch off their engines when idling for one minute. According to the Energy Savings Trust, London drivers alone are wasting £60 million per year by not doing so.

People tend to forget that leaving the engine running unnecessarily is actually an offence. The Highway Code says: "You MUST NOT leave a parked vehicle unattended with the engine running or leave a vehicle engine running unnecessarily while that vehicle is stationary on a public road." Some London boroughs are now imposing £80 fines if drivers spend a long time unloading their vehicles with the engine running.

Tim Anderson, Senior Knowledge Manager at the Energy Saving Trust, says,

"Turning off engines when it is anticipated that you will be stationary for more than a minute creates a number of benefits by reducing pollution and, by using less fuel, it also saves money," said Tim.

"This small, individual step can collectively make a significant difference and help improve life for everyone in London."

One of the most important places to start is the London taxi. According to Transport for London, black cabs account for about a quarter of vehicle soot emissions in central London, up to 15 per cent of which is caused by idling.

In a few years, this issue will be less important, as more cars get fitted with automatic stop/start systems. However, our experience is that they are very variable in their behaviour. Our long-term Ford Focus had a faultless system that worked as soon as the engine was warm, but our long-term Kia Picanto has one that works on less than half the occasions when the car is stationary, even when the engine is at the corect temperature.