Tokyo Xtreme Racer Zero is a car rpg and the third installment in Genki's Shutokō Battle series (there's a lot of xtrem racing in Tokyo you see).
You're a guy driving around the Tokyo highways and challenging random street racers. The series trademark is a truly anal level of customisation and its "spirit battle" system, where you challenge other shmucks driving around and you win by draining their health barm either by being ahead long enough or hoping they bump into stuff. Win or lose and you get money you can spend on customizing your car's body, transmission, drivetrain and other characteristics.
It's a solid gameplay loop. TK0 was pretty difficult to play at first because it uses a truly rotten implementation of the Ps2's pressure sensitive buttons, but switching to one of the shoulders or the RC car controls make it playable. I previously played the X360 game (renamed "Import Tuner Challenge"); while Zero obviously lacks some features, it has way more cars and highways and is decently more challenging,
which is good because the previously-mentioned game is really easy.