As a consumer of 30 percent of the petroleum used in the United States, the automobile is a prime target for energy conservation. Federal policies have succeeded in causing the automotive industry to increase fuel economy dramatically since 1974, while substantially reducing new car emissions and improving vehicle safety. Now, new policies are being proposed to induce automobile users to conserve gasoline. One such proposal, a 50-cents-per-gallon gasoline tax, has been injected into the national debate by Rep. John B. Anderson of Illinois. The Washington Post [editorial, Jan. 9] sees this proposal as the "simplest and most direct" way for the government to intercede for the involuntary driver. But reasons that go much deeper than consumer sensitivity to price make it unlikely that such as gasoline tax will achieve the intended result.

In an earlier period of energy abundance, we created sprawling metropolitan areas. Low-density suburban residential land use was accompanied by a dispersion along highways and beltways of factories, shopping centers and other businesses. This pattern of communities and work places was an offspring of the automobile-highway system. Now the mobility and way of life of life of our metropolitan areas, like our vast rural areas, is vitally dependent on that system.

The depth of this dependence is reflected in the facts that the automobile accounts for 90 percent of all personal travel; that more than 114 million automobiles are in service, or 1.8 vehicles per U.S. household; and that some 90 percent of the eligible U.S. population will be licensed to drive this year, according to a report by the National Transportation Policy Study Commission. The automobile has so ingrained itself in the life of America because it is the most flexible and responsive mode of transporation.

Even where least expected, among lower-in-come groups in densely populated places, dependence on the automobile is considerable. Thus, in lower-income areas of metropolitan New York, a study by the Regional Plan Association found that 40 percent traveled to work by auto, 35 percent by subway and 16 percent by bus. Those traveling by auto got there 20 percent to 50 percent faster and held better-paying jobs; and automobile use for travel to wrk in 1970 the same area was higher than that recorded by the 1960 census, despite the fact that auto ownership in these areas remained essentially static.

The New York example points up the importance of other factors in the cost of travel; trip time and convenience. The public accords a very high value to these factors and has consistently been willing to pay higher prices for them. Two energy squeezes, in 1973-74 and in 1979, indicated that automobile use is more affected by unavailability or perceived unavailability of fuel than by rises in the cost of fuel. Recent Federal Highway Administration data indicate that miles-traveled-per-car are up again, following the increased availability of fuel and despite dramatic increases in its prices.

Undoubtedly, every automobile user has a breaking point as far as price of gasoline is concerned. The point to be emphasized here is that you cannot pull the tooth without pulling its roots. Because the automobile is so inextricably a part of the way of life of so many in our society, the pain will radiate in many directions as that breaking point is reached.

The fact that monies collected in the form of the gasoline tax will be routed back to lower-in-come groups in meritorious but beside the point: the point is that, if the tax mechanism causes people to forgo use of their autombiles (unless there is a viable alternative, including ride-sharing opportunities and expedient public transportation) they will have to forgo other things or change where or how they live.

The "involuntary" drivers -- people who have to drive -- are not limited to the farm belt, the range lands and other rural areas. They are legion -- and most likely predominant -- in our metropolitan areas, where more than half the population lives in suburbs. The involuntary driver is not only found among breadwinners whose home-to-job routes are not served adequately by mass transit, but also among the housewives who have to deliver kids to activities, get to the doctor, the market, the shopping center on the beltway or the part-time job in a neighboring suburb. There are also lower-income city dwellers for whom the car offers access to much-needed recreation opportunities that might otherwise be denied them. (Do we know enough to distinguish between frivolous driving and that needed for mental health?)

The psychological and socialogical dimensions of America's involvement with the automobile have yet to be fully probed and understood. A recent George Washington University study for the Department of Transportaion of the behavioral and attitudinal aspects of car-pooling stressed the deeply rooted attachment people have toward their automobile, irrespective of income level. Many commuters would no sooner share a ride to and from work than they would consider sharing the privacy of their bath. Most Americans, if involuntarily deprived of their car -- and the privacy and sense of freedom and independence it may afford them -- would probably feel like a turtle without a shell.

The purpose here is not to advocate the automobile but to emphasize the essential role it has come to play in the nation's mobility and in the daily lives and activities of most households. Whatever we may think of suburban sprawl and beltway shopping centers, they exist and reinforce the auto-oriented life style. For our life style to change dramatically will require far-reaching changes in the nation's infrastructure. The automobile has very deep roots.

There is no question that the public should be encouraged to conserve gasoline, and there are many opportunities for people to do so. At the same time, a fresh and serious assessment should be made of the so-called "voluntary" driver population: it may be a lot smaller than we think.