High oil prices and high taxes on gas pushed the average price of gasoline to new heights in much of Europe this summer. Yet transportation experts in this laboratory of sky-high fuel prices say that many Europeans, out of necessity, habit or love, have proved surprisingly willing to bear the extra cost of driving. That raises questions as to how effective high prices by themselves can be in achieving the ambitious targets for reducing carbon dioxide emissions that European leaders have committed themselves to meeting.

　　Gas prices have persuaded some people to drive less. Traffic on the Eurostar train that links London and Paris was up 21 percent in the first three months of 2008. Gas purchases in Italy dropped 10 percent compared with the year before. Sales of gas-guzzling sport utility vehicles have plunged across the continent, just as they have in the United States.

　　But, at least so far, there are few signs of the wholesale shift away from current driving habits that environmental economists contend is needed for European countries to meet emissions control targets. Rental car companies say their business is up this summer. Many consumers appear willing to economize in other parts of their lives — eliminating vacations, movies, even birthday gifts — before choosing not to drive.

　　Although new car sales in both Europe and the United States have slumped this year, the number of cars per person has continued to rise, partly because many people now have more than one car, according to statistics from the Organization for Economic Cooperation and Development.