WHY DO GAS stations in Conshohocken have some of the highest prices in the region? And why would drivers choose to fill their tanks there?

Some of the area's most expensive pumps are found in the Montgomery County borough.

Three stations in Conshohocken were above $4 for regular gas yesterday, according to AAA Fuel Finder.

"We had no other area per se that has had that many gas stations over $4 a gallon," Catherine Rossi, manager of public and government affairs for AAA Mid-Atlantic, said yesterday.

She said prices can range because of zone pricing, meaning that some stations pay more for gas based on what zone they're in, Rossi said.

Zone pricing wasn't necessarily on the minds of three drivers interviewed yesterday at two of the high-priced stations.

Rick Platel, 30, of Frankford, said he was putting Sunoco's $4.29 regular gas into his Ford Explorer out of necessity: His tank was empty.

Platel said he doesn't put all the blame on the gas stations.

"It's what the oil companies are gauging," he said.

"It's the supply as much as the cost."

Gassing up at the same Sunoco, Leslie Rawling, 50, of Downingtown, said she usually looks to fill her Volvo XC90 based on location over cost.

Rawling needed gas in Conshohocken yesterday. She chose that $4.29 Sunoco over a less-expensive Lukoil nearby.

"After I pulled in here I looked at [the other station] and said, 'What am I doing here?' " she said.

In certain areas, Rawling said, stations seem to charge whatever they think people will pay.

"It's awful that the government is allowing this to happen and that one station can charge you 20 cents more a gallon right across the street," she said.

But some drivers avoid stations with the highest prices.

Paul Gregory, 25, who lives in Conshohocken, chose to fill his 1999 Ranger yesterday at a $4.09 Lukoil instead of at the Sunoco.

"It does make you a little anxious just thinking about it, especially getting to the end of the month paying bills," Gregory said. "I was going to travel to Baltimore over the weekend, but it costs too much."

Gregory said he tries to find a happy medium between a station's location and the cost of gas.

"I definitely try to look for the most reasonable price," he said.

Nearby, another Sunoco station in Conshy was selling regular gas yesterday at $3.97 a gallon.

John Tucholski, 24, who has worked at that station for five years, said the oil company allows operators only 4 cents of "wiggling room" per gallon.

"The individual owner cannot just be nice and say, 'Let me put it to $3.80.' They are kind of handcuffed," said Tucholski.

Last Monday, seven stations in the Philadelphia area were selling regular gas for more than $4 a gallon. By yesterday, the number had jumped to 107 stations, according to AAA.

Ross DiBono, executive director of the Pennsylvania Association of Gasoline Retailers and Allied Trades, said zone pricing is likely the cause of Conshy's high gas prices.

"The days when people are gouging consumers are over. If people are marking up higher prices, my guess is that they are being charged higher prices," he said.

"There is no reason for this, except that Sunoco thinks they can charge a higher price. What other business do you know that puts their prices in two-foot letters at the most visible parts of their business?

"There are no tricks here. Nobody is hiding prices from anybody in this business," he said.

William Choy, 46, of Plymouth Meeting, reports gas prices for the consumer Web site PhillyGasPrices.com on his way to and from work.

"I just figured that they were higher [in Conshohocken] because they are right off the Blue Route."

Sunoco spokesman Thomas Golembeski said that Sunoco prices its gas competitively based on the market, and says it is possible that stations in Conshohocken could be charged more because of zone pricing.