I don't know how you can say these cars lack ventilation, with those huge barn doors in the footwell. Open those on the freeway and it's like a hurricane.
I'm glad you brought that up.......I'm thinking that bad seals and fresh air leaks from "down there" on both sides' vents can dilute the hot air blast from the heater with cold vent air......right on yo' feets.
I also think that (at least partial) cardboard in front of the radiator would definitely help.
