I own a 1302 produced on 11 May 1972 and it has the vents. Based upon the 1302-1303 parts microfiche ALL 1302 and 1303 models with the larger than 1200 engines were all stamped with the vent hole. As for effectiveness, that is questionable. My car was in storage in Germany (Bavaria) for 39 years and 9 months so much is OEM. It had some work done after coming out of storage and some trim parts were stolen when the window rubber was replaced. My car is a 1302S Deluxe; Lapis Blue cloth upholstery, Marina Blue paint and non-perforated printed dot headliner. It has a crack-free padded dash, the large steering wheel chest protector with collapsing column, ATE front disc brakes and a Solex PICT34-4 carburetor. My fuel filter is located to the left and slightly over the transmission. The heater pipes are some what flexible plated, galvanized maybe, steel covered with a sewn insulation blanket. There are red rubber covers that help to seal in the heat at each end of the heater hose from the heater box to the car interior. I need two replacements. They feel like silicone rubber.
I have a friend in Germany that owns his mother's 1971 1200. It has no rear quarter vents but it is a Super Beetle body with the laid-down spare tire in the frunk. It does have the horn vents through the front fenders. None of the German built cars for '71 and '72 have the high back seats you see in cars for North America. My '72 has the low back seats and only directional signals on the front fenders. The parking light is in the headlight reflector. Directional signal lens in front and back are yellow, brake light is red. My car has the same size tail light lens as the 1968 models. The right rear fender may have been replaced since the rear tail light on that side is 25mm lower than the left side tail light. Rear fender rolled edges appear to be identical.
When I got my carin 2019 it had the original bias ply spare tire, Fulda 560X15, and the wheel was blue, not silver. The tire still has the little rubber tabs all over the side walls. I don't think it was ever used.