"Coupled with the appearance of the first streamlined cars (the Audi 5000s in 1983, and the Ford Taurus in 1986)"
This is incorrect.
North American companies started to pay more attention to aerodynamics and efficiency in the early 80's and it was 1984 that Ford released the new Thunderbird which was a huge departure from the box on wheels the 1983 version was. This car had a very low drag coefficient and I have to say, I really loved my old Turbo Coupe.
Saab has been wind tunnel testing their cars from day 1 and even their earliest models have very low drag coefficients and their 70's and 80's models can post numbers that will match and beat many modern cars.
European and Japanese makers have been designing cars based on aerodynamic benefits for much longer than North American producers although much of this research and development has gone into making sports cars and not daily drivers.