When you need one, or it's raining, they are hard to find but Shanghai has lots of taxis. And in spite of feelings to the contrary, they are obliged to operate within a certain set of rules, write Tan Xian and Kartz Qian.

Despite complaints that there are never enough taxis, Shanghai has thousands of cabs and strict government rules and regulations overseeing how they operate.

Shanghai now has dozens of taxi companies, differentiated by different colors. Mostly, the bigger ones have more veteran divers with about 25 percent able to speak simple English.

"As a girl, I loved the big companies,'' says Nova Wang, from Hong Kong, who has lived in Shanghai for 10 years. "The divers are more experienced, know their way around and negotiate busy traffic better. I also prefer the cabbies with stars."

Taxi drivers in Shanghai have to undertake strict exams and assessments to obtain their "stars'' which are issued by Shanghai Taxi Administration.

The cabbies are evaluated on aspects such as language, service and the condition of the car. The number of stars they have is shown below the rearview mirror.

The highest ranking is five stars, representing the taxi to service in Shanghai. Five-star cabbies are rare in the city.

"I used to prefer the big companies, but now I prefer the smaller firms as many of them don't mind if you smoke,'' says Ben Denton, an Englishman who has lived in Shanghai for seven years.

"Some of the taxis have great 'Chinglish' rules behind the driver's seat,'' says English teacher Oliver Knapman, from the UK. "It's a good idea to keep the receipt in case you forget something.''

It's important to understand a few facts about cabbies in Shanghai. For example, according to regulations, taxi divers should follow the route a passenger requests, if they do so.

Some cabbies still try a few tricks and they will often suggest several different routes.