What is a Glow-Off

, and one of the sponsors of the New York show. Mr. Panzarella, who saw his first neon-lighted car while doing repossessions in Florida a decade ago, modeled the event after auto audio competitions called Sound Offs.

''We're 10 years old,'' said Steve Hamilton, marketing director for Street Glow, ''and our sales have done nothing but double every year. Every generation has its own thing with cars. There were muscle cars for a different generation, and this is it for Generation Y.''

Unlike the street racers depicted in Hollywood films like ''The Fast and the Furious,'' glow cars are not built for speed.

''Performance is not very high on the list of priorities,'' Mr. Hamilton said. ''It's more about appearance. You take a relatively inexpensive small car and put money into adding onto it.'' Honda accounts for nearly half of the cars customized, but Toyota, Mitsubishi, Daimler-Chrysler's Neon and the Ford Focus are gaining. Some customers quote a rule of thumb for a hot car: improvements cost as much as the original vehicle, which is often bought used.

While speed isn't vital to the subculture, music is. Lighting is now tied to increasingly complex audio and video systems, which turn cars into miniature dance clubs on wheels. Strobes and tubes are wired to pulse in time to the rhythm of powerful bass speakers. Flat-panel displays are wired to game consoles and mounted on dashboards or seat backs to show racing games like Gran Turismo. The Glow-Offs, sometimes billed as ''automotive lifestyle events,'' usually include bands and D.J.'s as well as the dozens of conflicting sounds that emanate from the cars.

Mike Zimmerman of Lansdale, Pa., customizes cars for Blaupunkt, an audio equipment company, and brought an original Volkswagen Beetle to the Javits show. The car is accented with golden flames and stuffed with a new line of translucent Blaupunkt amplifiers that resemble first-generation iMac computers. ''I take this car everywhere,'' Mr. Zimmerman said. ''I'm on the road about 20 weeks a year.''

The lighting demands heavy-duty batteries. Some owners add capacitors under the hoods, and some use converters so they can plug their parked cars into household current for long-term displays. Most of the lights are rigged to be turned off for highway travel because many lighting schemes run afoul of local highway regulations. While irritating the authorities has always been part of teenagers' car cultures, ''this is good clean fun,'' Mr. Hamilton said.

''There's nothing these kids do with their cars,'' he added, ''that is more shock to another driver than encountering the bright high-intensity-discharge headlights of a new Mercedes or BMW.''

While glow cars are still a niche interest, they may prefigure the wider automotive future. At the Tokyo auto show last fall, Toyota and Sony displayed a show car called the Pod, which expresses its driver's mood by changing its lighting. Ford has developed a prototype called the Glo-Car, which is covered with L.E.D. panels that change color and brightness to express emotion as well as to indicate turns and speed changes.

''There is a trend toward self-expression,'' said Laurens van den Acker, director of concept vehicles at Ford, ''yet cars are inherently inflexible. Can we come up with a way that allows them to personalize their vehicle at the flick of a switch?''

For those who think smaller, there are Tireflys, tiny bulbs and batteries, made by Theory3 in Lake Buena Vista, Fla., that replace the valve-stem caps on tires.

Activated by motion, they make rolling tires look like glowing rings. At $15 a pair, TireFlys can even give an old Schwinn glow-on-the-go.