I bought a 3 door, 5 speed, 1.0L Geo Metro in 1993 for $8,000. I got 50 mpg out of it, it has 250,000 miles on it, and I still drive it today.
There is a distinct lack of such cars on the market now. The only way I can get a car that gets 50 mpg is to pay 3 or 4 times what I paid for that Metro.
I cannot afford that, neither can many others.
It's true these cars never marketed well, and current EPA regulations would likely not allow for them to be marketed as they were.
However, demand for used Metros has increased somewhat, as gas prices have risen.
Allowing/requiring the marketing of such cars, or comparable models, would be a net benefit to the nation, the ecology, and the people, despite their slightly dated emissions technologies.