I know very little about the 168. It was a 164 marketed in Asia. The difference is only in the 8 and 4...168 being lucky numerically. Simply thoughtful marketing. Unlike GM selling Nova's in Spanish speaking countries.
Excellent point jfournier. For those of you not in the know, No va is spanish means, doesn't go!!!! Great name for a car. Apparently the numerical sequence ending with a 4 is unlucky in asia. I'm not sure that 8 is lucky, but rather it was to get away from the 4.
In Asian (Chinese) culture, the number 8 is considered lucky or bringing forture (wealth). In San Francisco you will see many cars with personalized license plates with lots of 8s in them and asian drivers. For example: