Diesel engines used to be dismissed by most drivers as too dirty, noisy and slow even to consider as their next car purchase. But their greater efficiency is attracting a record number of motor-ists, according to figures published to-day by the Society of Motor Manufacturers and Traders.

By 2011 sales of diesel-powered cars will outstrip petrol-powered cars as millions more drivers seek to avoid the heavy tax penalties announced last week for fuel-inefficient vehicles.

Diesel accounted for 40.2 per cent of the 2.4 million cars sold in Britain last year, compared with only 13.8 per cent in 1999. It has already overtaken petrol in terms of the total fuel consumed by all vehicles in Britain. Last year drivers bought 25.5 billion litres of diesel and 24 billion litres of petrol.

Despite costing 5p-10p a litre more at the pumps than petrol, diesel proves more economical for most drivers because it delivers 10-20 per cent more miles for the same fuel.

The showroom tax of up to £950 for the biggest gas guzzlers, which was announced in the Budget last week and comes into force in 2010, will encourage more drivers to switch to cars with lower carbon dioxide emissions.

If they choose a petrol-powered car, they will usually have to accept a smaller, less powerful model in order to move into a cheaper road tax band. But if they opt for diesel they can continue to drive a larger car and still benefit from tax concessions for producing less carbon dioxide per mile.

They will have to pay about £1,000 more than for a similar-sized petrol-powered car, but high mileage drivers will make that back in savings on fuel costs within two years.

A petrol-powered Ford Focus 1.6 will deliver 42 miles per gallon, while a diesel version of the same car will achieve more than 60mpg.

The “dash to diesel” was the main factor behind a small fall in average carbon dioxide emissions of new cars last year to 164.9g/km, down 1.4 per cent from 167.2g/km in 2006.

The society admitted that new diesel cars still emit more air pollutants, such as particulates and nitrogen oxides, than similar-sized petrol cars. But Paul Everitt, its chief executive, said that European regulations on exhaust emissions were forcing manufacturers to fit better filters to diesel-powered cars. By September 2009, with the introduction of Euro 5 engines, there will be no difference in the particulate emissions of diesel and petrol cars. By 2014, with the introduction of Euro 6 engines, parity will almost be achieved on nitrogen oxides.

Mr Everitt called on the Government to abolish the 3 per cent surcharge in the company car tax regime for drivers choosing diesel cars. He said: “With diesel engines rapidly being cleaned up, there will no longer be any justification for this penalty.”

The AA said that the popularity of diesels had leapt because drivers no longer had to accept lower performance. Paul Watters, the AA’s head of roads policy, said that the victory of an Audi diesel at Le Mans in 2006, which prompted the race organisers to change the rules, had demonstrated the transformation of diesel technology.

He said: “The introduction of turbo diesels and systems to reduce vibration and noise were the biggest factors. You used to hear a diesel car coming a mile away because it sounded like a tractor. Now, you would be hard-pushed to tell a diesel from a petrol car if you were standing next to them at traffic lights.”

The UK Petroleum Industry Association said that diesel was more expensive than petrol, despite having the same duty rate, because oil companies had failed to predict the rise in demand.

A spokesman said: “They made a lot of investment in producing unleaded petrol in the 1980s and 1990s but petrol demand peaked in 1990. The pace of diesel growth has surprised people.”