My 1985 Honda Civic got 50 miles per gallon.
They went backwards on gas mileage to line the pockets of the oil thug industry.
No, that's not why the went backwards.
Cars in the 1970's got horrible gas mileage because gas was so cheap. When the oil crisis hit gas prices skyrocketed. All of a sudden consumers demanded more fuel efficient cars and automakers produced them. By the early 1980's you had a lot of small, efficient cars available. But once gasoline got cheaper again people once again demanded large vehicles, and the automakers gave them what they wanted.
http://inflationdata.com/Inflation/images/charts/Oil/Gasoline_inflation_chart.htm
The oil companies make money either way, no conspiracy required. When gas is cheap people buy bigger cars. When gas is expensive they buy more efficient cars.