While building 60150 Pizza Van, I noticed that the first few steps of building the eponymous vehicle have you place lime green 1x2 tiles in specific positions and black 1x2 plates in others:
These then get covered completely by light grey 2x16 plates (although you can still see them just behind the wheels and mudguards of the finished model):
A similar use of tiles appears in other LEGO City vehicles, such as the ambulance in 60204 LEGO City Hospital.
Why are tiles used in parts of the chassis construction? Is it to (slightly) reduce the number of studs holding onto the tubes of the 2x16 plates, thereby making them easier to remove when taking things apart later?