30 years ago, there were a few cars that got 25 MPG, primarily the VW Beetle but also a few other imports like the Honda 600 and perhaps a few Datsuns. I don't know of any American made cars that got that kind of mileage then but it's possible there were one or two.

Gasoline prices today are actually cheaper in real dollar terms than they were at many other times in the past. Referring to the Inflation Calculator link on the Consumer Price Index webpage, here are some of the numbers:

Year / Price Then / In Today's Dollars
1965 / 0.26 / $1.48
1974 / 0.54 / $1.96
1978 / 1.00 / $2.74
1982 / 1.34 / $2.48

Gasoline prices doubled in 1973 following the OPEC oil embargo. Where I lived, the gas prices at independent stations went from 26 cents per gallon to over 50 cents. For the first time, millions of people were interested in buying cars that got good gas mileage because the pundits were predicting prices would soon be $2 a gallon (pundits were as inaccurate then as they are today).

The American made small cars at the time were the Vega, Pinto, and Gremlin - winners all. Millions of people suddenly expressed interest in imported cars like the Honda Civic, Toyotas, and Datsuns. Imported cars jumped to 20+% of the market from the low single digits.

In 1978 following the overthrow of the Shah of Iran, prices doubled again to over a dollar a gallon. At the same time, the switchover to all unleaded gas was underway (unleaded gas cost about 10 cents a gallon more than leaded regular in 1978). Government mandated emissions controls and mileage standards forced the auto companies to switch over to computerized systems. This development, along with other things like 5 MPH bumbers, airbags, etc. have driven up the cost of most cars faster than the rate of inflation.

I bought my first new car in 1974 (a Civic hatchback) for just under $3,000 total driveaway cost (taxes included). It was a fun little car with a 4 speed, no air conditioning, and able to get 28-32 MPG. Had the price of a Civic simply kept up with inflation, that car would cost $10,880 drive away cost today. Try buying a new Civic for that price. A basic Civic is well over $12,000. Throw in the higher taxes and you'll find the cost of even a basic car is over 20% above what it would've cost had the price risen solely due to inflation. Someone has to pay for those government mandates and of course, it's the consumer.

The National Academy of Science estimates that today's mileage standards result in about 2000 additional highway deaths each year. That too is a price people are paying to comply with those government mandates.