Just had to bring up cold temperatures. 04 Cavalier wasn't too bad, only two wires for the speaker door, wife wanted remote entry, so had to add two more wires. And while I was at it, have a roll of pretinned 16AWG neoprene test lead wire, stays flexible even under the coldest temperatures. So replaced the speaker wires as well.
Not so with the Cruze, has a ton of wires going into the doors, and using cheap plastic for insulation. So when its cold, I open and close those doors very slowly.
Actually I wanted to buy another coupe, only two doors to worry about instead of four. With our grandkids, perfer to use my Supra with good old fashion lap belts, a struggle to put these in with the Cruze, also have a bar in the rear for that top strap. Release the seat back latch on either side of the Supra, seat back goes forward and slides to the front effortlessly, so no problems in strapping them in.
Tooling, are you even familiar with the latest versions of AutoCad, open your print, push a button, and controls a numerical controlled machine. Go home, and when you come back in the morning, its done.
Even way back in the early 70's designed an automatic camshaft grinder, no more skilled machinist, just a kid smart enough to put a blank in and pus a button, hang around, well others to look at, when it was done, take out the ground one, and put another blank in. Been awhile, but would think to day they replaced that kid with a robot.