In cold weather it isn't airflow from the windows, but usually thermal loss from the glass itself.
I have found that some custom cut matts of Reflectix/Coolshield, fitted with magnets on the edges and backed with some felt-like cloth go a long way to minimizing chill coming off the glass. They also minimize the amount of warm humid air hitting the glass so condensation is minimalized. They pull off and stow easily during the day to soak up sunlight and restore visibility.
It helps that my side and rear windows are covered with perforated white vinyl, so from the outside, nobody can see them.
I took a standard sun shield made of stiff foil-like Reflectix and covered it with the same black felt like material.
I can put the foil side out in summer and I put the black side out in winter, mostly because it is less noticeable in winter and the foil side is bouncing heat back into the living space.
As for doors, do the dollar bill test.
Place a dollar bill at the edge of the door gasket and close the door; watch your fingers!
If the bill slides out easily you have a gap. Do this in multiple places along the doors.
You can use some closed cell adhesive backed weatherstripping to seal gaps (added benefit: the vehicle will be quieter going down the road and parked).
If the gaps are large you can get rubber self-adhesive "D" profile weather stripping to help seal the gaps.
There is usually space around doors to install it adjacent to existing weatherstripping.
