Daimler AG's Mercedes-Benz, Volkswagen AG's Audi and BMW's flagship BMW brand all posted year-on-year volume gains of above 35 percent in the country in September, they said.

Globally, BMW and Daimler have been suffering double-digit declines this year through August, while Audi has cut its sales contraction to slightly below 10 percent.

"The sales figures for premium carmakers give a better indication of where the market would be were it not for government incentives," said Ulrich Winzen, chief analyst for forecasting and consulting at Essen-based firm R.L. Polk.

"At the latest by the end of 2010 or early 2011, though, luxury carmakers should return to their previous growth paths, albeit from a lower level. Until then, China will certainly help them bridge the gap."

Thanks to the new E-Class saloon that nearly doubled sales to 1,700 units, Mercedes-Benz's volume in China grew by 56 percent to about 6,800 vehicles last month, albeit from a lower base than its two German rivals.

It shifted 1,600 of its top-of-the-line S-Class model that carries fat margins, a gain of 12 percent. Sales of its SUV models jumped 73 percent to 1,200 vehicles.

This helped boost the brand's overall volume in the first nine months by 41 percent to 45,400 vehicles.

"Mercedes-Benz is the fastest-growing luxury brand in China, both in September and in the three quarters since January," a spokeswoman for Daimler said.

Daimler also sold some 1,200 Smart ForTwos since the brand was launched in April.

BMW boosted sales of its core brand by 35 percent to 7,628 vehicles in the month and by 32 percent to 59,460 in the first nine months.

Audi sales rose 37 percent last month to over 15,000 vehicles -- the first time it breached that level in a single month in China. That helped it easily crack the 100,000-mark through September, increasing volumes by a fifth so far this year.

Volkswagen's luxury brand is far more heavily dependent on China for its performance than Mercedes or BMW thanks to VW's strong presence in the market over the past two decades and Audi's weak U.S. sales compared with its two biggest competitors.