Hybrid highway

Economy | Fueled by pump prices, a growing number of car owners are pushing reluctant auto manufacturers into stealth mode | John Dawson

Ever since Stephen McGrogan picked up a screwdriver and turned his Toyota Prius into a stealth car, he's had problems. More accurately, others have had problems with him.

"I was in Orchard Supply going to pick up some stuff," he said, when an employee asked Mr. McGrogan to follow him through the warehouse. Mr. McGrogan flipped off the gas engine and rolled into the California chain's home improvement warehouse on what he calls "stealth mode," or silent battery power. "We were rolling along and I thought, 'This is going to bother him in a little while.' Sure enough, he spun around and stopped. I rolled up next to him, put the window down and said, 'It's electric.'"

While the hybrid gas-electric Toyota is sold in other countries with the capability of running off batteries with the engine fully off, Toyota disabled the function on Priuses sold in the United States. The move drove Mr. McGrogan, a Bay Area electrical engineer, and hundreds of other Prius owners to spend less than $100 for a kit, pick up a screwdriver, and rewire the car to unlock the function.