From Grant Johnson of Horizons Unlimited: “There is a thread on the Horizons Unlimited HUBB that is all about crossing into China. Currently – as in at last word a few days ago, Jan 5 2006 – it’s not possible LEGALLY to cross on your own with a vehicle without a government guide. It HAS been done illegally, and a VERY few people have gotten away with it – but most people simply get refused entry at the border….Rentals are also not possible LEGALLY. You must have a Chinese drivers licence, which is not easy to get, as well as a whole lot of other obstacles. MUCH more on this subject at http://www.horizonsunlimited.com/ubb/Forum33/HTML/000291.html“
As he stated, some people have gotten through. Here’s a post from Aug 2004: “we crossed the border between Sary Tash, Kyrgystan, and Kashgar, China, 4 days ago. The border is Irkeshtam. The only thing we needed was a 30 day tourist visa and an international driving licence. No chinese guide, nor chinese driving licence nor chinese number plates. Border is officially open since may 22 2004. That’s what one border guy (the only one speaking english) told us. We were TOLD to spread the message: Welcome to China”
On the same forum there is information about locations and costs for guides. I’d look into it, because I suspect that, like all countries “in transition,” crossing borders successfully may depend on the mood of the border guard and how much confusion there is currently around the official stance. In my experience it is always better to try this at remote and obscure borders than well-traveled ones. When I motorcycled China, I stayed in China, so I have no personal experience with crossing borders in or out of that country.
