From Jalopnik, a preview of the new Ford F-650 XUV, designed specifically to handle your transportation needs during the rise of the living dead. BRRRAAAAAIIIIINNNSSSS!!!!
One touch that would be handy that I don't see: razor sharp panels that extend from just below the window line, which would be about "head height" for the zombies.
Of course, despite the fuel tanks on the bottom, I can't imagine you'd get very good gas mileage. Will there be enough undead-free QuickTrips to gas 'er up?