I can't make a comparison because I've never owned a 6-series, but I've owned a '72 CS for the last year and a half with basically no problems to speak of. There are the occasional electrical glitches that go on, but the car is almost 30 years old so I don't blame it. In my case it was the rear windows that stopped working. Dependability wise, I'd drive it anywhere as long as it wasn't raining much. I'd consider most CS's fair-weather cars.