Detroit — Throughout most of the 1970s and early '80s, fuel economy ranked as the No. 1 consideration among new-car buyers, who were appalled by skyrocketing fuel prices and uncertainty over whether or not they could find a station to fill up.
How times change! Acceptable fuel economy, regardless of car size, has become something to be expected. From the foremost slot, mileage has now sunk to fourth or fifth place, depending on whose survey one uses. Trouble-free operation, initial purchase price, financing charges, and even car size and luxury level have come to mean more to many buyers than Environmental Protection Agency (EPA) mileage numbers.
With the current worldwide oil glut and tumbling fuel prices, at least until the new nickel-a-gallon federal fuel tax boost took effect early in April, mileage could well sink even lower in the standings.
That does not, however, suggest that the global drive toward still greater automotive fuel efficiency has ended. On the contrary, there is solid evidence that tomorrow's buyers will find their fuel bills shrinking no matter what size cars they buy.
A survey of US auto manufacturers strongly indicates that the goal of greater fuel efficiency will go on unabated, for two chief reasons:
* Major programs toward that end cannot be drastically altered even if that were desired.
* Whatever it costs, fuel will still be expensive.
Beyond that, federal fuel economy standards in the United States and other types of incentives to boost fuel efficiency in foreign countries, such as penalties for high-horsepower cars, demand that mileage gains continue to be a noble quest.
Finally, judged by the roller-coaster history of fuel prices in recent years, pegged to oil prices posted by the Organization of Petroleum Exporting Countries (OPEC), no one can say for certain what fuel-price trends will be in the long term.
It may stretch your memory, but 10 years ago gasoline was selling for an average of 41 cents a gallon. Then came the October 1973 OPEC oil embargo. Five years later 70 cents a gallon was common. The second oil crisis, precipitated by the ouster of the late Shah of Iran in February 1979, sent prices soaring straight upward, to about $1.50 a gallon by 1981.
Since then, it's been downhill to an average of around $1.30 last year and now to the $1.15-to-$1.20 range. In some parts of the US, notably the Southwest, it's not uncommon to find regular-grade gasoline selling at less than $1 a gallon.
And even with the new 5-cent federal tax, prices at least in the short term are expected to stabilize or drop lower. Most oil experts predict that OPEC, which dropped its price from $34 a barrel to $29 in March, will succumb to further pressures and slice another $4 to $9 off its per-barrel prices. That would be enough to sink pump prices to the 80-cent level.
Only those with short memories, however, will take for granted that this price break will last forever. So what happens next?
First of all, larger cars stand to benefit most during the near future. Already doing well despite the four-year recession and 10 percent-plus unemployment, they are expected to remain strong now that mileage is not the end-all for many motorists.
Significantly, standard full-size cars now boast double the mileage they achieved only a few years ago, and their prices haven't risen as fast as smaller models.
To many Americans needing more passenger and luggage space, that combination spells ''bargain'' in capital letters.
To keep pace with demand for larger models, each of the US Big Three - General Motors, Ford, and Chrysler - has altered its production plans to produce more of these models. In some instances, they've moved back plans for dropping older models and replacing them with lighter, more fuel-efficient, state-of-the-art cars.
But there are compelling reasons to continue the trend toward smaller, high-mileage cars in the long term.
''People are going to be coming back into the market, and we're betting they'll go for entry-level (smaller) models,'' says Robert C. Stempel, head of the Chevrolet division. ''A lot of people under 35 have never driven a big car, '' he adds, supporting his view that smaller models will sell on their own merits.
F. James McDonald, president of GM, observes: ''There'll be a greater demand for larger cars as oil prices go down, but I don't know if big cars will make a (long-term) comeback. People have come to enjoy smaller cars.''
Harold A. Poling, Ford executive vice-president in charge of North American automotive operations, anticipates weakness ''in the smaller end'' and strength in the higher-price and -size segments near-term, but predicts that ''the trend toward smaller cars will continue,'' on grounds that Ford and everyone else must still meet federal fuel-economy standards, which rise from 26 miles per gallon this year to 271/2 m.p.g. in 1985.
Louis E. Lataif, Ford division chief, adds: ''Affordability also is an issue. More people can afford a Tempo (which will start at about $7,000) than a Crown Victoria (which starts at well above $10,000).
''As more people come back into the market and have to make car payments, it's not going to shift (to larger models) too fast.''
Moreover, adds another Ford executive, for many people fuel remains a major budget item - and expensive - even though prices are lower.
Beyond all these reasons, US automakers still must battle toe to toe with Japanese importers, whose fuel-economy excellence is now taken for granted. And technical improvements, such as turbocharging smaller engines to provide greater performance without greatly sacrificing mileage, makes smaller cars increasingly attractive. What fuel costs in Europe
Before Total tax Tax per gal Italy $1.16 $1.76 $2.92 Belgium 1.30 1.45 2.75 France 1.29 1.46 2.75 Denmark 1.25 1.45 2.70 Austria 1.25 1.27 2.52 United Kingdom 1.19 1.32 2.51 Switzerland 1.27 1.24 2.51 Sweden 1.36 1.11 2.47 W. Germany 1.07 1.09 2.16 Source: MVMA and Ethyl Corp. Note: Prices are averaged for various gasoline grades as of early 1982 and converted to U.S. gallons and dollars from local measures and currencies.