You cannot drive with an International Driver's Permit in mainland China; China has not signed the convention which created IDPs. You need a Chinese license to drive in China. Note that Hong Kong and Macau licenses are also considered to be foreign and having one of them will not allow you to drive in the mainland.
The easiest way for a foreigner to get a Mainland license is to take the following action: in Hong Kong, convert your foreign license into a Hong Kong license for about 120 USD. Then, go to Mainland (Guangzhou is probably the easiest place) and convert your HK license into a Mainland license. It is doable to pass the test all by yourself. The test can be done everywhere in at least English, and the English questions for preparation are not hard to find. In most places, private tutoring is allowed given common sense and reasonable care: that means in practice that at least one person in the car must have a valid license but not necessarily the driver.
In mainland China, traffic drives on the right-hand side of the road. Hong Kong and Macau drive on the left.
The physical condition of roads and road maintenance varies greatly from municipality to municipality with the Western provinces being poorer than the east-coast and the Guangzhou region. As the building and maintenance of roads are mostly funded by local government, you may notice a sharp change when crossing provincial borders. Places with decent economy has superb infrastructure.
When possible, drive near the middle-right of the road as drain covers are usually stolen. The side of the road could be a mixture of pedestrian, bicycles and tricycles, animals, drain well without covers, and like in India, sometimes farmers use part of the road to dry the grains.
In major city roads traffic is often congested, even on the myriad of city ring roads (except those on the outer fringes of the city). Beijing comes in at the worst (comparatively), despite five ring roads and nine arterial expressways. Shanghai ranks relatively better, with elevated expressways and tunnels.
The congestion is far more complex than that in Western countries. Bicycles swarm everywhere even in the dark. In many areas, there are also lots of motorcycles. In the smaller cities, anything from tractors to bullock carts may turn up!
Chinese drivers routinely go through red lights if there is no opposing traffic. Pedestrians do not count as traffic; just honk at them to get out of the way or swerve around them. It is also moderately common to run red lights even in the presence of other traffic.
Expressways and express routes in China are a godsend, with traffic signs in both English and Chinese, emergency facilities, service areas, sufficient filling stations, plenty of exits, high speed limits, and the relative lack of traffic jams. However, when one does occur expect to wait several hours or in rare cases even days for the traffic to clear as damaged cars or trucks or usually not taken off the roadway after the accident resulting in kilometer upon kilometer of jammed roadways. Furthermore, this will result in drivers jockeying for position and jamming the emergency shoulder adding further waiting time to the traffic jam and potentially more accidents.
Most visitors find they have enough trouble surviving Chinese traffic without actually taking the wheel. It is generally best to just rent a car with a driver or employ a driver if you buy a car. Because of Chinese wages, the cost of the driver is quite low.
