For both the extruded polygon and the cylinder face 0, is the bottom, face 2 the top and face 1 the edge joining the bottom and top. Remember that currently the car body and its wheels are built lying down
An extruded polygon has three surfaces top, bottom and extruded sides, face 0 is the top, face 1 the extruded sides and face 2 the bottom.
Is there an error in the first description?
face 0 → bottom or top?