Unlock HW Prototype 12
To unlock HW prototype you must complete all the missions in adventure mode.

Get All Worlds
Finish Challenge 18 and find the hidden key.

Get All Cars
Finish Challenge 8 and hit 11 bonus stunt items.

Get All items
Finish Challenge 7 and hit 30 barrels.

Infinite Health
Finish Challenge 17 and hit 179 barrels.

Infinite Turbo
Finish Challenge 4 and get 8 zappers.

Infinite Ammo
Finish Challenge 18 and hit 50 barrels.

Timer Speed
Finish Challenge 12 and hit 60 barrels.