German arch-rivals BMW and DaimlerChrysler's Mercedes Car Group raced to record March sales as the boasting battle for premium car supremacy heats up.

A new model offensive helped sales at Daimler's flagship Mercedes-Benz brand to gallop ahead by a fifth and nose ahead of its Munich-based rival's core BMW brand by less than 3,000 glossy vehicles last month, its first lead in months.

But deliveries of BMW's Mini - which is built in the UK at Oxford - beat sales of Daimler's Smart minicar, keeping BMW group sales, including luxury marque Rolls-Royce, ahead of those at Mercedes, which also includes Mayback.

Nevertheless, Mercedes sales are gaining momentum while BMW's breakneck growth starts to decelerate.

"Both manufacturers are profiting from strongly rejuvenated product lines. Demand in the overall car market is rather restrained," said Michael Raab, an automotive sector analyst at Bank Sal Oppenheim in Frankfurt.

"BMW's growth is being driven primarily by the BMW 3 Series, but the basis effect is lessening given the model changeover last year.

"This means it will not be able to maintain its growth rates this year. I expect unit sales to rise six to seven per cent in 2006," he added.

BMW group sales rose by 13.5 per cent in March to a record 144,316 units, amid double-digit percentage growth in the United States and BMW's home market of Germany and solid demand from increasingly well-heeled buyers in China.

Deliveries at its core BMW brand rose by 16.8 per cent to 122,509 units, while those of its Mini brand fell by 1.7 per cent to 21,760 cars amid expansion work at Oxford.

For the first quarter, BMW group sales rose by 13.9 per cent to 332,923 vehicles, keeping it ahead of the 295,000 cars sold by Mercedes, a gain of 12.2 per cent.

Sales of the BMW 3 Series grew by 54.2 per cent in the first quarter to 122,691 vehicles.

Mercedes sales rose by 17.4 per cent to 138,400 units in March. Mercedes-Benz brand sales gained 21.4 per cent to 125,400 units, while sales at its Smart small car brand fell by 11.3 per cent to 13,000 cars.

Mercedes is riding a sales wave after launching revamped versions of the M-Class offroader and S-Class executive car last year.