I think in most cars outside air comes through the vents even when the fan is not on - as long as you don't have the recirculate activated.

But the Mini has absolutely no air coming through the vents unless you turn on the fan. Is it supposed to be like this?

 

Yes.

 

So, if I have fan off, and there's a F150 truck in front of me smoking black stuff out, am I safe from that? I always press the recirculate when I see that happen even when the fan is off, but then it starts the fan. I wish the recirculate button was placed on the steering wheel in place of the useless voice command button.

 

It's worse in the cold, the recirculate only last for 10 seconds below -10'C.

Yes, turning the fan off seems to work well, but the windows fog up quickly in a little car.