See Boiling Point: Road to Hell Hint, Cheat-code here!

Unlimited gas for cars
Press and hold [Z] to turn off engine while driving. Car is still driving but no
gas is used.

Bring up the console, and type in one of the following codes:

addarmor # - Adds more armor (1-99)
addhealth # - Adds more health (1-99)
addammo # - Adds more ammo (1-99)