For all the complaining about rising in gas prices, some people just can’t park their fuel hogs and switch to gas-sipping hybrids.

For folks such as Joe Seay, having a massive ride is the way he gets his job done.

The landscape business owner plows through the Tennessee Valley in a Chevrolet 4500 pickup with six wheels, chugging regular unleaded gas at the rate of 7 miles per gallon.

“I’m trying to make my truck lighter by only loading the equipment I’m going to need that day,” Mr. Seay said. “I’m looking at maybe going to another type of vehicle, but the one I have now is convenient.”

Like Mr. Seay, others are finding ways to cut their gas use.

Pablo Lucas of Aqua Terra Landscaping drives a Ford F-150 pickup that he said requires more than $100 in gas a day. All the landscaping machinery it tows uses more than 20 gallons a day, he said.

Lamar Milling, owner of Plush Lawn Care, faces a similar plight. In business for 18 years, he’s been forced to raise prices, and his wife said the couple is cutting back on at-home expenses to save money at their business.

Mr. Seay is passing the expense along to his customers, too. He already has raised his prices 15 to 20 percent, he said, and he has instituted a fee for estimates and really small jobs. He said he doesn’t like to do it.

“You don’t want to raise prices, because there’s only so much people can afford,” Mr. Seay said. “If you keep raising prices, eventually people will find someone else.

“We haven’t lost any business, but some of the homeowners don’t like the new prices,” he said. “But you’ve got to have that minimum price because of the gas.”

Until now, most motorists could endure the high prices, said Dr. Matthew Murray, a University of Tennessee economics professor. Now, consumers are starting to pay more attention and looking to conserve, he said.

Many companies that rely on massive gas use simply will have to adjust, Dr. Murray said.

“They were all still in business and doing well up until 2003 and 2004, because gas prices had not really adjusted for inflation,” he said. “I think we’ve peaked at $4-a-gallon gas ... and I really hope I’m right, because last year I bought a boat with an 8-cylinder, 4.2 liter engine. I get five miles to the gallon on the lake.”

On Wednesday, Nathan Byram and his cousin, Bubba, were on Chickamauga Lake for the first time this year. Filling up his boat, he said, he ran into a tremendous increase in gas prices compared to the year before. It cost him about $65 to fill up his boat’s tank, he said, and he’s just puttering around in a 15-foot, flat-bottomed aluminum craft.

But when you’re behind the wheel of a massive recreational vehicle that comes with a big price tag, fuel isn’t a huge concern, said Fred Hardwick, parked this week at Shipps RV Center and Campground in East Ridge. The Dandridge, Tenn., resident drove his 26-foot recreational vehicle — considerably smaller than others parked in the campground — about 150 miles for his granddaughter’s medical treatment.

“It’s still cheaper for me to travel in this than it is to get a hotel room,” Mr. Hardwick said. “That’s not including the original investment, though.

“You see plenty of RVs in parks, but you don’t see many on the road these days,” he said. “They’re just planning their routes better and staying in the park when they get to where they are going.”

RVs, like many other vehicles that use a lot of gas, are in a tight market, he said.

“These things are easy to buy but really hard to sell right now,” said Mr. Hardwick, who traded a larger, diesel-powered RV for his current smaller, more fuel-efficient gas-powered one a year ago.

Mr. Seay and Mr. Milling said they are looking at more fuel-efficient trucks, but they believe it will be hard — if not impossible — to sell their current gas hogs.

The increase in gas prices comes at a time when major automobile manufacturers are changing their business models, shifting from larger vehicles to more fuel-efficient models.

General Motors announced last week that it would shutter four plants that make trucks and SUVs, a sign that even big automakers see a very tight market for vehicles that aren’t fuel efficient, Dr. Murray said. GMC has said it would examine selling its Hummer product line, according to the Associated Press.

“The shaking out is already taking place,” Dr. Murray said. “The fact that airlines are getting rid of planes and that GM is closing plants is an indication that big business sees this as a long-term trend.”

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