[Kostas']

If you want only On Foot:

pawn Code:

if (strcmp(cmdtext, "/race", true) == 0) {
        RemovePlayerFromVehicle(playerid);
        SetPlayerPos(playerid,x,y,z);
        GameTextForPlayer(playerid,"Welcome to race!",4000,6);
        return 1;
    }

If else On Vehicle:

pawn Code:

if (!strcmp(cmdtext, "/race", true)) {
        new Float:x,Float:y,Float:z;
        GetPlayerPos(GOTOPLAYER,x,y,z);
        if (GetPlayerState(playerid)==PLAYER_STATE_DRIVER)SetVehiclePos(GetPlayerVehicleID(playerid),x,y,z);
        else SetPlayerPos(playerid,x,y,z);
        return 1;
    }