TOKYO -- When Sadayoshi Ishi drives his Hummer, he takes precautions. He has installed a navigation system that shows wide-open streets in green and more dangerous narrow streets in pink on a computerized map inside the truck. Periscopelike monitors on each side-view mirror alert him to obstacles.

Mr. Ishi isn't dodging land mines in a desert war zone. The 48-year-old Japanese cartoonist is trying to navigate Tokyo's urban jungle of streets too narrow for his 7-foot-wide vehicle. "I broke out in a sweat every time I drove it," says Mr. Ishi. He now drives his Hummer just once a week -- to golf games -- on a predetermined route.

In land-scarce Japan, it's not easy to own an oversized SUV, but some people insist on it. WSJ's Amy Chozick reports.

Mr. Ishi is one of a growing number of Japanese who are spending more than $100,000 for the military-style H1 Hummer. Mesmerized by the mammoth trucks shown in TV news coverage of the war in Iraq, they are determined to overcome the special problems of driving in Japan.

The Hummer is the civilian version of the U.S. military's High Mobility Multipurpose Wheeled Vehicle, or Humvee, made by A.M. General Corp. The South Bend, Ind., company started selling a limited number of Hummers to civilians in 1992. In 1999, General Motors Corp. gm +0.53% General Motors Co. U.S.: NYSE $37.95 +0.20 +0.53% July 11, 2014 4:00 pm Volume (Delayed 15m) : 6.13M AFTER HOURS $37.91 -0.04 -0.11% July 11, 2014 4:49 pm Volume (Delayed 15m): 72,174 P/E Ratio 11.34 Market Cap $60.86 Billion Dividend Yield 3.16% Rev. per Employee $712,105 07/11/14 GM Hires Infiniti Chief de Nys... 07/11/14 Infiniti Motor President de Ny... 07/10/14 German Auto-Parts Maker Launch... More quote details and news » bought the license to use the Hummer brand and market the A.M. General-made Hummer as the $125,000-plus H1. The civilian H1 is almost exactly the same as the Humvee, except for a few added features like air conditioning and a stereo system, and a few that are subtracted, such as fittings for attaching machine guns and grenade launchers.

The vehicle was trendy in the U.S., but as gasoline prices soared and consumer tastes shifted to smaller, more fuel-efficient brands, demand waned. Last year, GM stopped selling the H1 world-wide and began pushing the more practical H2 model. Launched in 2002 and also made by A.M. General, the H2 starts at $56,000 and has a slimmer body, smoother ride and more lavish interiors than the H1. In 2006 GM itself began manufacturing the H3, a scaled-down version of the H2 about the size of a Jeep Cherokee that capitalizes on the Hummer name and appearance and has a base price of $30,000.

Last year, car dealers in Japan sold about 1,400 Hummers, four times the number sold in 2005 and triple the number of Ferraris sold in 2006. Some Japanese -- about 100 last year -- buy their Hummers directly from dealers in the U.S.

Japan makes up just a small part of GM's 52,000 Hummer-brand SUVs sold last year, but it is a surprising growth area. American cars have typically not wowed consumers in Japan, except for a few niche models like the boatlike Cadillac sedans and classic Corvettes. GM, the largest U.S. brand here, sold fewer than 10,000 vehicles last year.

At the Tokyo Motor Show going on now, GM is showcasing a new Japan-only version of the H3 with the steering wheel on the right since Japanese drive on the left side of the road.

The Hummer appeals to drivers who are "looking for something big and mean that looks like you've got real wheels," says Shiro Horie, editor in chief of American Edge magazine, a new Japanese publication dedicated to American cars.

It was a rebellious spirit that motivated Iwao Makino to buy a royal blue H1 Hummer in 2002. He had seen it on news footage of the war in Iraq and heard it could wade through 60 inches of water and survive a 15-foot drop from an airplane. The 33-year-old owner of a small business that sells computer systems knew that driving on rough terrain is a common practice among Hummer owners in the U.S. But he found that off-roading is banned in most parts of Japan for environmental reasons. "I'm just waiting for a typhoon or big disaster to hit Tokyo so I can use my Hummer to rescue people," says Mr. Makino. His biggest thrill now is dodging retailers' street signs when driving to the grocery store and taking his dogs to the park.

While U.S. H1 drivers also have problems squeezing into parking garages and driving on narrow roads, such problems are way worse in Japan, where minicars make up a third of the car market.

Passionate owners like Messrs. Makino and Ishi exchange driving tips at the Hummer Owners' Club of Japan, a support group designed to help H1 owners care for their cars. The club was co-founded by Tsuyoshi Ishitobi, one of Japan's early converts, who bought a fire-engine red Hummer in 1995.

In the early days, the 51-year-old assistant manager at a technology firm spent his time measuring the width of the streets in his neighborhood. Because there is no place to park his Hummer at his house and most of the streets in Tokyo are so narrow, Mr. Ishitobi keeps his Hummer in a garage an hour-and-a-half away. He uses a tiny Suzuki miniwagon to get there on weekends.

"My lifestyle completely changed," Mr. Ishitobi says. In his spare time, he coaches new drivers who come out to his suburban garage on how to care for their Hummers and navigate narrow roads. He helps them install complex machinery, such as high-resolution video monitors that instantly display the width of streets on a GPS, or global positioning system, screen.

Parking is a big concern among H1 owners because the H1, at around 6&frac12; feet tall, won't fit into most Tokyo parking garages. Shuichi Asai, a 38-year-old apparel-industry executive, tore up his wife's garden to build a carport large enough to park his beige H1. When his wife protested, he appeased her by buying her an ocean-blue H1 of her own. He says she had always liked his Hummer but never expected such an expensive gift.

It costs about $115 to fill up the 32-gallon gas tank of an H1 in Japan, compared with about $90 in the U.S. In addition, Japan has an environmental law that requires owners of gas guzzlers like the H1 to pay $1,000 tax annually. Another problem: Since GM stopped selling the H1 last year, spare parts are hard to find.

Hummer club members order H1 parts like suspension balls and joints in bulk from Lynch Hummer in Chesterfield, Mo., the largest H1 dealer in the U.S. Together, the 60 members spend about $88,000 a year on parts and call Lynch Hummer almost daily.

As the H2 and H3 models proliferate in Japan, one looming concern for H1 owners is that their vehicles won't stand out as much. Yoshiaki Matsubara, a Hummer club member who owns a restaurant and car museum and wears a hat decorated with a skull and crossbones, owns five H1 Hummers and says that until recently, children ran after the car and waved to him as he drove by.

"I don't get as much attention as I used to," sighs the entrepreneur.

—Ayako Nomura and Naoto Okamura contributed to this article.

Write to Amy Chozick at