The M12 (known to everyone as merely the "Warthog") is your stock set of wheels. You'll get these more than you'll get everything else. Like the manual says, it's fast - but definitely takes a practiced hand to control, and should be turned gently. A gunner (Marine or a friend) increases your effectiveness exponentially; a passenger, only marginally. Also, note the Warthog's run-people-over-for-instant-kills feature.