In Grandprix4 folder and in gpxpdata folder open keys.ini file with notepad.
there i entered my choice as like this
Game_CamTrack=Z
Game_CamCockpit=X
Game_ControlSteerRight=RIGHT
Game_ControlSteerLeft=LEFT
Game_ControlBrake=DOWN
Game_ControlAccelerate=UP
with this choice i can play using up ,down ,right,left arrows keys on keyboard.
and rest are default.
before u do this make a copy of keys.ini file
===================================================================================================================
i7 950@4GHZ 1.24V|Asus P6X58D-E|Dominators 10GB(2GBx5)1600C8|Corsair H70|Corsair 800D|Corsair HX850|EVGA,Zotac GTX 2x470|VX2433W FULL HD|X-Fi Plantinum|Creative S750 Gigaworks7.1|NZXT Sentry 2|7TB