There’s a cabin air filter for the ventilation system in modern cars (I’m not 100% certain of whether older cars had those), though I don’t know how good a job those do on engine exhaust.
I vonder vhwere ze vindows vent?
Subaru vehicles still maintain the triangular vent windows…they just don’t open any more. But they’re there on all their cars, and it does provide better visibility around the a-pillar, especially when the driver is making a left turn.
In cars with no AC, weren’t the Vents a good way to “cool” the car when it was raining hard?
At least as far as my memory goes; yes. The still air box for the regular vents/dash vents must have been located in such a fashion that they didn’t get as much and having the windows wide (the 4-60 AC Unit as we called it) allowed as much out as in. With the vents it seemed like the fumes didn’t just enter but lingered for some reason.
No filters at least on the 50s/60s cars I owned.
See my post #16; it depends. They could help quite a bit but you had to learn how to set and adjust them. Like outside mirrors back then (the kind that you adjusted manually sometimes mounted in odd places like the fenders) YMMV widely.
How, exactly, did they direct air onto the windshield?
Set like this it really did draw a flow across the inside of a windshield and work as an addition to the “defrost” setting. If you did both sides the same way it also created a sort of central flow keeping the driver and passenger “draft-free”.
Camaros had them in '67 . They did not in '68. Why? At first, GM said it was styling. Eventually, they admitted it was simply a cost-saving measure. Other makers followed suit. The other reasons mentioned earlier in this thread were not considered then.