Tokyo Xtreme Racer Zero is an 'interquel' between Tokyo Xtreme Racer 2 and Tokyo Xtreme Racer: Drift, and has enhanced sound and graphics. The game was released in Japan but was also a limited release in North America. The game was released in a PAL version in Europe and Australia under the title Tokyo Xtreme Racer (not to be confused with the Dreamcast title of the same name).
This is the first game in the series that has been released on a platform other than the Dreamcast. Zero was to originally be released on the Dreamcast, but was then cancelled and moved to the PlayStation 2.
Source: Wikipedia, "Tokyo Xtreme Racer: Zero", available under the CC-BY-SA License.