said by BonezX:agreed, some cars are designed to live with this stress, remember how they used to ship chevy vega's (nose down!) said by telco_mtl:
car companies also go to great lengths to prove damaged cars in transit dont make their way into the market, a few years back a boat full of mazdas rolled on its side just off the west coast. As we all know cars are VERY well strapped down on those ships but lying on their side for a month isnt all that great for the engine.
They invited the media to see the cars crushed on the dock.
actually most of it is the potential for abnormal stress damage. cars are designed to sit a specific way within a specific range of angles, when tilted over like they were it would cause stresses on parts not normally stressed(one strut mount over 100% designed compression, other under tension), as well as potentially bending frames and other important components, the engines and trans would be fine(weren't moving not submerged), mounts suspension and body not quite so much.