Pump nozzle in hand, Lisa Atkins keeps a close eye on the digital display rapidly adding up the pounds. Gone are the days when she'd routinely fill the gas tank to the brim. She now has to be more cautious.

Ms. Atkins says the surging cost of fuel is discouraging her from taking to the wheel each time she needs to travel. "I'm driving less and less," she says. "Me and my nan [grandmother] go shopping together.... Weekends we try to just leave the car outside and walk everywhere local."

She's not the only one reacting to the $9 per gallon gas prices. Britons are driving less, opting instead for public transportation, car pools, and a reduced number of overall car trips. Recent surveys show that Britain is leading the way with the change in driving habits, probably because pump prices here are higher than the global average. British demand for gasoline fell by around 8 percent year-on-year in January and February.

Across the globe, governments are dealing with a string of protests by truckers, fishermen, and others stung by price hikes. The movement will escalate in Britain on Wednesday when thousands of truckers descend on London to demand urgent financial relief, with the threat of blockades and civil disobedience. Their protest follows Operation Escargot in France, during which truck drivers drove at a snail's pace to protest the high price of fuel, causing major traffic jams through June.

According to the International Energy Agency (IEA), a Paris-based think tank, the decline in driving is the same across Europe. "The rest of Europe is pretty much in line with that, although in the UK the effect is slightly higher because prices are higher [here] than elsewhere," says Eduardo Lopez, an oil market demand expert at the IEA.

Gas stations in Britain are reporting unusual changes in buying patterns, says Alex Wells of the Petrol Retailers Association. "Buying in the morning is down, but not so much in the afternoon," he says. "This is because second cars are being used less, the stay-at-home mums are driving less. They are doing the weekly shopping in one hit."

Sheila Rainger, deputy director of the Royal Automobile Club Foundation, an independent motorists' association, says the effect is clear on the roads, too. "We have a perception that people have cut back on optional journeys," she remarks. "We are starting to see a fall in congestion and in traffic."

Meanwhile, carpooling in the UK, which is still a relatively niche concept, is rising. Liftshare, a database company that matches journeys for people looking for carpooling possibilities, reports that demand has shot up in recent weeks. Earlier this year, the company was averaging between 200 and 300 new members a day, but that has shot up above 500. One day last week, 582 new members signed on, according to spokeswoman Cecilia Bromley-Martin. While around 5,000 people registered in April, the number was close to 15,000 in June, she says.

"People are discovering the many benefits of car sharing because the fuel price is a real worry to a lot of people," says Ms. Bromley-Martin, adding that carpooling can save the average commuter 1,000 pounds ($1,993) a year.

Many environmentalists have quietly rejoiced that the high cost of fuel is apparently achieving what governments have largely failed to: a reduction in carbon emissions.

But not all subscribe to this logic. Tom Burke, an environmental scientist and former government adviser, says high pump prices "inevitably fall hardest on people who can least bear them, instead of on governments who took wrong decisions."

"You can't just say it's a good thing that prices go up and people will do more sensible things," he says. "Older people, people already at the bottom of the pile, will find it harder ... to live and anyone who welcomes that has lost their humanity."

Mr. Burke adds that the British government should have started upgrading public transport a long time ago so that a proper alternative was available for people who chose to leave their cars at home. As Ms. Rainger puts it, switching car for bus is only acceptable "if the bus goes where you want it to and if it's affordable." In Britain, that's not always the case.