NEW car buyers are all set for the 55 plate rush and superminis and diesel cars will lead the way, according to figures released by SMMT.

The industry expects around 420,000 new cars to leave showrooms this month, making it the second busiest month of the year.

And as fuel prices continue to soar, more buyers are thinking about diesel vehicles and diesel new car sales continue to defy a drop in sales across the industry.

Since 1999 diesel sales have nearly trebled as buyers enjoy between 20 and 30 per cent better fuel economy, as well as more model choice and greater engine refinement.

Demand for supermini models and small family cars has also soared.

In 1997, superminis accounted for 575,597 units at a time when the average price of petrol was 61.8p per litre.

At the end of 2004 unleaded cost 80.9p and sales of models like the Ford Fiesta and Vauxhall Corsa had risen to 839,604 units, up by more than a quarter of a million.

Today, many forecourts charge more than 90p per litre. But while fuel prices continue to hit motorists, the good news is that fuel consumption is improving.

In 1998, a new car averaged 34.5 miles to the gallon; in 2004 this had risen to 37.8, an improvement of nearly 10 per cent.

Christopher Macgowan, SMMT chief executive, said: "Fuel costs have risen steadily in the last decade and now petrol has breached the four pound a gallon mark for the first time.

"So, while the mantra for many September customers will be big and beautiful regardless of fuel costs, for many more bangs for your buck will be the priority."