Given China's love affairs with global luxury brands and homegrown social media, it's no surprise that the former should use the latter. The surprise is who does it best.

L2 Thinktank, an industry group which researches digital advertising, has taken a closer look at the 'social engagement' of 100 international brands and ranked them accordingly. The winner is Audi, followed by Burberry, BMW and Volvo. In fact seven of the top ten are carmakers.

Cosmetics brands, which featured prominently at the top last year, have started sliding down the ranks.

One of the things Audi does right is using as many social media outlets as possible--it maintains a presence on six different social media sites.

Another piece of research published this week shows why that is so important: China has no clear leader in social media and social networking, according to data collected over the past six months by Jiathis, a social sharing button provider.

Sina Weibo, widely viewed as the country's leading microblog, has seen user activity levels stall while Tencent Weibo, its main challenger, appears to be catching up. Qzone, a social network run by Tencent, is also thriving--measured by both 'sharing' applications and clickrates. Renren and Kaixin, China's two Facebook equivalents, are neck and neck in user activity, but far behind the microblogs.

It is this vibrant but chaotic marketplace which seems to prove challenging to some global brands. The main mistake which caused some to slide in the China social engagement ranking was a lack of updates to their digital presence, according to the L2 survey.

Another problem highlighted by L2 is working with search engines. While there is no question that Google is the site of choice in most markets around the world, Baidu, with a more than 80 per cent market share in China, cannot be neglected here. The L2 study shows that many international brand which have positioned themselves very well in Google's search results fare poorly on Baidu.

The conclusion: be everywhere.