Doppler Truck

Doppler Trucks (or DOW, Doppler on Wheels, as they're known in the real world) are radar trucks that reveal all locations of a specific item in your current zone when you crash into them:

Red unlocks all Challenges

Blue unlocks all Liveries

Green unlocks all Vista Points


 * In-game they take the form of plain, white Bonesaw trucks.
 * Their locations are awarded after certain races in each zone.
 * Your map shows their icons, and you can generally find a heliport to bring you in closer
 * You'll need to keep referring to your map for the general direction to go, but once you get close their icon will show up on your GPS HUD.