Prius

Ok, if you're going to redesign a system - like the ignition system on the Prius - you should have some instructions - or not hand one over to a novice without instructions. Last trip (LA) I was given a Prius as a rental. No instructions. I could see the key didn't turn. I hit the power button and stuff would light up then turn off when I hit it again. Somehow the first two times I magically got the car to start, but it wasn't until 5 minutes into my frustrating trial and error process that I figured out you have to have your foot on the brake when you push the start button to actually have it start the engine.

Oh, and the engine switching between electric and internal combustion (making me think the engine had died) was unnerving for a newbie.