Some hybrid car owners go to great measures to figure out ways of getting as much as possible out of a tank of gas from Bloomberg News

Toyota Motor Corp. says its Prius gasoline-electric hybrid car gets about 55 miles to the gallon, making it one of the most fuel-efficient cars on the road. That's not good enough for Takashi Toya.

Toya, a 56-year-old manager for a tofumaker in central Japan, puts special tires on his Prius, tapes plastic and cardboard over the engine, and blocks the grill with foam rubber. He drives without shoes and hacks into his car's computer -- all in the pursuit of maximum distance with minimum gasoline.

Toya is one of about 100 nenpimania, Japanese for "mileage maniacs," or hybrid owners who compete against each other to squeeze as much as 115 miles per gallon out of their cars. In a country where gasoline costs more than $4 a gallon, at least $1 more than the U.S. price, enthusiasts tweak their cars and hone driving techniques to cut fuel bills and gain bragging rights.

"My wife thinks I've joined some strange secret society," Toya said at a nenpimania gathering in Nagoya in central Japan.

Mileage maniacs aren't alone in pushing the limits of hybrid vehicles. As U.S. automakers General Motors Corp. and Ford Motor Co. race to introduce their own models, first rolled out by Japanese companies in 1997, engineers at Toyota and Honda Motor Co. are trying to boost hybrid performance to maintain their advantage.

Hybrids combine a conventional gasoline engine with an electric motor. The motor powers the vehicle at low speeds, and the gasoline engine kicks in as the car accelerates. The motor uses the motion of the wheels to recharge the batteries.

Toya, nicknamed "The Shogun," said he drove 1,000 miles (1,600 kilometers) on a single 13-gallon (49-liter) tank 17 times last year, an average of 79 miles per gallon. At the advertised efficiency rate, a driver would get 715 miles per tank.

Toya isn't the best, though. A woman from Akita prefecture, nicknamed "Teddy-Girl," is cited on mileage maniac Web sites as getting almost 116 mpg. That's enough to drive from New York to Wichita, Kan. -- 1,386 miles -- without refilling.

By comparison, a 2007 two-wheel drive Ford F-150 pickup running at peak efficiency burns through five times as much gasoline over the same distance.

Since the 1997 release of the Prius, the first mass-market hybrid, owners in Japan and elsewhere have fiddled with their cars to raise mileage and shared tips, including the best driving techniques, over the Internet. The mileage maniacs strive to perfect what they call the "pulse and glide" driving method.

Pulsing and gliding demands sensitivity when pushing or releasing the accelerator, so only his big toe touches the pedal. On a chilly Saturday in Aichi prefecture, not far from Toyota City, Toya removes his right shoe to demonstrate. Toya accelerates, or pulses, to 29 m.p.h., then glides down to 25 m.p.h. before pulsing again. The car uses no fuel when gliding.

Toyota plans to introduce a new Prius by 2009 that will be smaller and cheaper, said Koji Endo, an auto analyst at Credit Suisse First Boston in Tokyo.. The mileage maniacs say they look forward to the challenge of improving its fuel efficiency.

The vehicle will be high-tech," enthusiast Mimura said. "I think it'll be more difficult to hack."