All right guys, it's about damn time this thread be bumped. Besides, I've got some new food for thought in case the world suffers what Max Brook calls a level three outbreak.
I've concluded that the best gas powered vehicle for carrier either survivors or anti-zombie sweeper groups is a armored personnel carrier. A simple SWAT version would suffice since a gun turret isn't going to do all that much damage to a horde of ghouls. It would be able to plow though most of the abandoned cars on the roads without damage and even if you run out of gas it's going to be a damn fine fortress for your team. Not to mention the fact that you could run through an entire city worth of "Zak".
Picture included in spoiler tag
As for weapons you've a choice for either low tech or high tech, a simple an reliable M1 Garand would be about as good as you can get. Obviously worked well enough for the American GI's that it was used all the way though the Korean War. You couldn't do wrong with this weapon, especially if you manage to find one equipped with a bayonet.
Then there's the M4 Carbine, awesome weapon but it's still an assault rifle and the less self-controlled in your team might be tempted to click the select fire to full auto and spray wildly into the group. On the plus side there's a hell of a lot of accessories that you can modify it with. A telescoping stock for close quarters would be a god send, and a grenade launcher would be good for taking care of non-ghoul "problems".
M1 Garand at the top, M4 Carbine at the bottom.