The air continuity path between the sills-rockers and passenger compartment is a requirement of the electrocoating processes. This air path siphons air from the densest spray from wet and often salty roads as these electrocoat process holes are directly over the front wheel track. This mechanism of building-up of the aggressive microclimate on internal body panels is not appreciated by automotive designers.
The jacking points are usually incorporated into the sills-rockers and the adjacent area often requires reinforcement. Therefore, usually associated with the jacking point, or in very close proximity, to the jacking point is an electrocoat drainage hole. Most manufacturers' jacking points are usually slung beneath the sill-rocker and so present an extra perpendicular protuberance in the high speed wheel spray, which atomizes on impact with the protuberance. This atomized spray is sucked into the drainage hole adjacent to the jacking points and causes corrosion of the internal jacking point reinforcement. (reference)