But the launch of its low-lead, four-star petrol and its low-sulphur diesel demonstrated that Britain has one of the oldest and dirtiest fleets of cars in Europe.
Shell said that it sold petrol and diesel fuels in other European countries which were considerably less polluting than its new UK products. It does so because their more green-minded governments ensure there is a market for them.
Shell's low-lead four-star, which will sell at the same price as the conventional product, is intended for the 28 per cent of British cars which cannot be converted to run lead-free. Only Italy has a greater proportion of cars in this category. The oil company, which jousts with Esso for lead position in UK sales, said the new fuel would cut a car's lead emissions by half without changing performance.
Lead is put in petrol to boost its octane rating and to act as a lubricant, preventing piston valves from damaging engines. The metal forms a microscopically thin layer on cylinder parts which receive severe wear. All cars sold new since 1990 have hardened valves and can run on lead-free petrol.
Shell conceded it was possible to cut an old unconverted car's lead emissions by a quarter without engine damage by ensuring that every fourth time the tank was filled, it was filled with cheaper lead-free petrol.
Leaded petrol is being phased out because it can reduce children's intelligence and alter their behaviour. Sales are falling but they still account for 37 per cent of the petrol market in Britain.
Shell's other new UK product is a diesel fuel which produces three-quarters less sulphur dioxide - a pollutant gas which harms health and causes acid rain. Next year, all companies selling diesel in the UK will have to meet this lower sulphur standard by law. The company says the new diesel will also lower emissions of particulates, microscopic particles now thought to be among the most dangerous air pollutants.
In the rest of Europe, Shell sells a no-lead four-star petrol for older cars which cannot be altered to take conventional lead-free petrol. But in Britain one major discount petrol station chain, Save Service, has started selling a no-lead, four-star petrol at 80 of its 1,200 stations - not because of its environmental advantages but because it has spotted a money-making niche.Reuse content