When the taillight of Laura Musall’s five-year-old Nissan Altima burned out, she hoped to avoid the repair shop by letting her husband replace it at home. It seemed simple enough: Buy a bulb, pop off the cover and make the switch.

But her husband struggled to remove the plastic casing, and when he used a screwdriver to pry it off, it shattered. What came next was even worse. Her Nissan dealer wanted $250 to order a new one.

Musall, a real estate agent from Fishers, Ind., figured “10 bucks, we’d be done.” “But apparently,” she said, “it’s not a do-it-yourself thing if you don’t know what you’re doing.”

Car owners looking to trim expenses are sidestepping the mechanic and plunging into their own repairs. Or trying to, anyway. Their efforts can backfire, costing more in the end and creating do-it-yourself horror stories.

Mechanics say they’ve seen it all in recent months, including incorrectly applied brake pads and antifreeze poured into engines.

“A lot of people, they’re in dire straits,” said Pam Oakes, owner of Pam’s Motor City Automotive in Fort Myers, Fla. “They try to do this stuff at home in their driveway.”

The results can be frustrating, and sometimes outright dangerous.

Beth Riggs, who lives near Lebanon, Ohio, took her Chevy Trailblazer SUV to a car-savvy neighbor nearby who charged $500 to replace her front and back brakes, far less than the going rates at nearby repair shops.

Later, on a highway ramp, her car suddenly froze up and pulled to the side of the road. The problem? Riggs says her neighbor neglected to put a certain part on a bolt of the wheels, setting off a chain reaction that caused the tires to lock up.

The car had to be towed, and Riggs ended up paying an additional $400 to have it fixed at a suburban Cincinnati auto shop.

While well-intentioned, many people forget that today’s cars are vastly more complicated than models made just years ago. Most are so computer-controlled that owners can’t spot problems without access to specific tools and data programs, said Dave Striegel, owner of Elizabeth AutoCare in Elizabeth, Pa.

Even jobs that were once simple, such as changing the oil, can take hours to complete now.

“They’re not able to do nearly the work that they used to do — it’s even going beyond the heads of a lot of technicians who aren’t keeping up-to-date,” Striegel said.

Even so, some car owners remain undeterred. On Yahoo, queries for the terms “car repairs” and “salvage auto parts” are up 77 percent and 99 percent respectively in just the past month, according to the site’s data.

The urge to cut out the middleman extends to even the wealthy, said Stephen Viscusi, a New York-based author and career consultant. “We feel the need to be frugal and save money,” he said.

But that doesn’t mean repairs come easily. Viscusi tried to change the oil on his Mercedes- Benz sedan — and wound up with it all over his face, a situation he likened to an episode of “I Love Lucy.” He also struck out replacing spark plugs on his BMW.

People who try the at-home tinkering are usually out of work or low on cash.