"The top reason for at least 50 percent of customers to choose an Audi is they use it as a company car, even though they buy it in their own name," an Audi saleswoman surnamed Li told The Time Weekly.

At the 2013 Guangzhou auto show, Audi outlined its new target customers - "thinkers, creators and leaders".

But Audi is also believed to be suffering from its vague brand image as Chinese customers mature.

"It advocates technology and the future but I wonder whether such vague things can appeal to customers," said Wang Jin, a senior auto reporter at Securities Daily.

"Fans will respect Mercedes-Benz due to its history and feel BMW's passion for speed and driving pleasure. What can Audi use to attract private customers?"

He said Audi is losing the marketing race to many other premium automakers, adding both Infiniti's "Dare to Love" campaign and Volvo's emphasis on health, greenness and safety are more impressive than Audi's "Vorsprung durch Technik" - or progress through technology

Competitors

It comes as Audi's rivals continue to gain on the leader. BMW had a 23 percent growth in the Chinese market in the first half of the year and Mercedes-Benz had 36 percent. Audi registered a 17.8 increase in the period.

In addition to competitors from its home country, latecomers are also gaining traction. Infiniti sold 13,954 vehicles on the Chinese mainland in the first half of the year, a 130 percent surge year-on-year, and Volvo - now owned by Chinese automaker Geely - saw its sales reach 38,555 units, a 34 percent rise from the same period last year.

Although their sales numbers are now small, industry experts believe they pose a formidable challenge to Audi as they offer customers new choices.

"One important reason for Audi's dominance in China's premium car market is there were few brands to choose from. Now the situation has changed.

These so-called second-tier premium brands will deal a blow as heavy as, if not heavier than, BMW and Mercedes-Benz," said auto reporter Zeng Gaofei from the Legal Weekly.

"Among others, Volvo will be a major rival. It is good value for money yet has done a better job than Audi in safety".

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