History indicates they could also return to their old habits if prices continue to drop, once again steering gas guzzlers onto highway entrance ramps as though crude oil never hit $147 a barrel.

There are already signs that getting 60 mph has become less important to some consumers in Utah and nationally, Yet, many experts associated with hybrid vehicles and alternative energy hope the latest effort to break petroleum's control over our daily lives might succeed despite evidence that past efforts puttered to a stop once oil became more affordable.

Although motorists interviewed Wednesday in downtown Salt Lake City said they had altered their driving habits in the face of higher gasoline prices, at least a couple said they might revert to old practices once prices drop noticeably locally.

Anou Oudanonh, of South Jordan, said $4 gasoline prompted his wife and him to park one of their cars, with Oudanonh taking her to work in their smaller vehicle. Although he hasn't noticed much of a price drop to this point, once gas comes down Oudanonh said the couple will consider driving separate cars again because of the convenience.

Alex Chester, who was filling up his Mercedes at a Phillips 66 station, said if gas prices go back "into the three's" he will consider putting premium grade back into his car instead of the regular grade he went to with the run-up in prices.

As for those who have chosen to rely on public transportation, some say they will stick with it, while others might not.

The Utah Transit Authority has seen a 7 percent increase in ridership this year on its buses and the TRAX light-rail system, but it also has been steadily increasing fares because of its higher fuel costs, with another due in October and potentially another in January.

Paul Lawrence, of Bluffdale, waiting Wednesday at a downtown TRAX stop, said the fare increases will cause him and wife, Jessica, to weigh the cost of TRAX tickets versus driving when they want to travel to downtown Salt Lake City.

"We do consider" the price of UTA tickets when making a decision on using TRAX or a car, he said. "It would depend on how many people we have."

But for David Hewett, whose employer subsidizes half the price of his monthly UTA pass, the fare increases make little difference. "It's still a good deal," he said.

The fear among conservationists is that this year's spike in oil and gasoline prices might not be enough to permanently change consumers' driving habits.

"In the past what we've seen is oil shocks based on political reasons,'' said Wes Bolsen, chief marketing officer for Coskata, an ethanol refiner in Warrenville, Ill. ''Now, it's a supply-and-demand issue. With China and India in the market, no one is talking about $40-a-barrel oil.''

With the price of oil off nearly $30 from its record high of almost $150 a barrel, auto buyers nationally have instantly responded by showing less interest in hybrids such as the Toyota Prius.

Searches for the Prius on Cars.com have plunged more than 50 percent since peaking in May. ''There is a direct correlation between what people are searching for and gas prices,'' said Steve Nolan, a Cars.com spokesman.

America has traveled down the alternative energy road before. When oil prices soared in the 1970s and late 1980s, the idea of oil independence captured the popular and political imaginations. But those sentiments quickly faded once prices dropped.

Alternative-energy developers hope the situation will be different this time, arguing that demand from emerging economies will keep prices sufficiently high to force drivers to drive less.