Nasty unethical trick to take a rental car and butcher it essentially. Reasonable non destructive testing of rentals is probably common at the same time by many companies. .

Also they seriously broke the conditions in the rental contract. Some lack of fundamental ethics are involved here. It almost sounds like they physically took the car apart. To examine everything. What is also troublesome is obviously they thought they could get away with it.

Mercedes is also very wealthy company to put it mildly. Their income stream percentagewise from car manufacturing is very small potatoes to them overall.