Porsche began work on the project immediately, having a prototype of the vehicle ready within the month, but realized during development that it would not be enough to just reinforce the Beetle's chassis to handle the stresses that military use would place on it. In order to guarantee adequate off-road performance of a two-wheel-drive vehicle with a 1,000 cc FMCV 1 engine, it would have to be lightweight. In fact, the army had stipulated a laden weight of , including four battle-dressed troops, which meant that the vehicle itself should not weigh more than . Porsche therefore sub-contracted Trutz, an experienced military coachbuilder, to help out with the body design.