Hello y'all,
I want to try to list steps that car makers could/should take to improve the fuel efficiency. The most obvious would be to mold the plastic on the front of the vehicle to be smooth and round, with grill openings that are sized (and placed) only as required to cool the engine. Similar to the original VW Passat:
...or the original Ford Taurus:
Sealing all the seams and joints (with gaskets or backing flanges) in the high pressure areas of the vehicle.
I'll add more later, when I have more time.