A study by AutoBild reveals that modern crumple zones can actually hide serious damage to a car's structural integrity because of the way they're designed. There are two issues: the first is that crumple zones don't just deform in the case of an accident, they are now constructed to bounce back into shape after the collision; the second is that crumple zones are now so large, by government mandate, that crumple zone deformation might extend to points quite distant from the actual impact. By returning, even partially, to a pre-accident state, it is claimed that inspectors and mechanics might not realize how much damage has actually been done, nor exactly where.
AutoBild used a laser to assess the integrity of a car that had been in an accident. Hidden underneath bodywork that was only mildly scuffed they discovered a buckled frame. According to the magazine, a visual inspection even by an experienced mechanic wouldn't discern the damage. In fact, unless a mechanic was using a specialized and expensive machine to ascertain the extent of the damage, it probably wouldn't be caught. It is akin to the issue with helmets, wherein an accident that only scratches the helmet can render it useless. However, it's much easier to replace a Shoei for a few hundred than an entire car because of a fender bender. .
[Source: Auto Express]