The North American version of TXR3 has an error which makes it impossible to face one of the rivals in Osaka through normal means. There is a wanderer named "Whirlwind Fanfare", who requires the player to have 100,000,000CP to face him. Since the player can only have a maximum of 99,999,990CP, you can't face him, and since "Whirlwind Fanfare" is one of the 600 wanderers required to beat to face the final boss, the game is unwinnable without the use of a GameShark. The Japanese version did not have this error.
Source: Wikipedia, "Tokyo Xtreme Racer: 3", available under the CC-BY-SA License.