Actually automakers do take the under-body of cars into consideration. Case in point Porsche, have a look under a 911 and you will see its perfectly flat.
True this is a supercar company, but other lower companies, like Toyota, Mitsubishi, Subaru, and Honda also do the same thing.
Under many...
yeah its amazing how sensitive knock sensors are, and how quickly modern ECUs respond to them. just tapping the block with a screw driver is enough for the knock sensor to "hear"
Thats an interesting case though