Turn Cones into Mines:

 For  explosive  action, quickly  press L, R, L, R, L, R on  the  SETUP
 screen.  This  code  turns  the cones into mines that blow up anything
 that hits them. Drive safely! 

Turn Tracks Upside-down:

 To turn the  track  upside  down, quickly press Up, Right, Down, Left,
 Down, Right, Up, Left on the SETUP screen. 

Foggy Night 

 Go to the Options screen and change "Fog" to the Heavy setting.  Then
 hold all four C buttons and  press  right  on the  Control  Pad.  You
 should now have access to Foggy Night.