Good point and one I hadn't
Good point and one I hadn't thought of, Frank. The car has not yet been built in prototype form, only proof of concept, so that's likely an issue that will have to be addressed. I have operated a fully hydraulic powered (no engine/motor, just compressed hydraulics) crane lift before, however, and it was only loud when exerting a lot of force (i.e. lifting heavy loads) and was nearly silent when swiveling or raising/lowering empty riggers.
I have also seen hydraulic-assisted (using the Parker system) refuse trucks in action and didn't note any more noise than is normally associated with the diesel engines on board, though I did note that the air brakes were much quieter.