It's getting tight. You can measure it yourself. 3 Series BMW just under 2000mm, A6 2090mm, Ford S-Max 2160mm. Of course, you can still fold in the side mirrors, but whether that’s really desirable... Nah, I’d invest in a wider gate.
Depends on the car. A Sharan won't fit through unless the mirrors are folded in. It will probably be very tight for a Passat as well (if it fits at all).
Can you already align the car straight in front of the garage to drive in or do you drive in at an angle? If the latter, then definitely wider. In the first case, accuracy is key or you need new mirrors more often.