Huh I had a BMW 540, driving along, all of a sudden vapor billowing from under the hood. Temp gauge had spiked almost instantly. Driving later LA ---> Phoenix with a BMW antenna engineer, testing satellite radio. "Oh, that gauge is fake. The computer looks at the actual temperature and outside temperature and the load on the engine. If it seems normal it just sets the gauge to the middle" and then you cannot see it climbing up until the computer freaks out and pegs it.
That was one of the beginnings of my disillusion with BMW, others being how all their sound systems sound like hollow dog poop, and their turn signals don't turn off after a lane change (which even a cheap Hyundai can manage).