cRiPpLe_rOoStEr, they came out with armored versions of the HMMWV that may have equaled what was on the current trucks, but in truck versus IED, the lighter it is, the higher it would go, the higher the clearance, the greater the amount of force will dissipate, and a flat bottom absorbs all of the blast, while a V-shaped hull would direct some of it outwards. So, current gun trucks are heavier, with a higher clearance, and have V-shaped hulls, with all of the problems that come with added weight and a higher center of gravity.
This is the latest HMMWV, with a V-shaped hull:
This is the M1117, which the Army has used since 1,999, and some say we should have had in Iraq and Afghanistan, instead of the HMMWV:
