THEY'VE GONE car-crazy at the National Geographic. Explorers Hall is wall to wall with mementos of the golden age of motoring, before the dream of auto-mobility grew into a planet-consuming nightmare.

Suppress your environmental awareness and check your social conscience at the door. This is a party celebrating the sort-of centennial of the automobile and to hell with the hangover. Oh, they've got a solar-powered car and some chat about fuel-efficient engines, but that's just window dressing. This is a love story, and it's irresistible.

The centerpiece is a 1903 Jackson touring car, a 20-horsepower beauty whose unsprung box frame reminds us why they called them horseless carriages. On every hand there are memorabilia of early automania, and toy cars that will torment you young whippersnappers who were born too late. There are, for instance, 15 pedal cars.

The visuals include Mack Sennet shorts, dancing hot dogs from the days of drive-ins, and sequences of truly horrific race-car crashes. There's auto-motif jewelry, junk jewelry and junk. They didn't leave out anything, hardly.

But have a care not to stand too close behind middle-aged visitors, some of whom may suddenly start kicking themselves as they recall letting go of, say, a '39 LaSalle touring car, a '47 Plymouth business coupe, a 64 1/2 Mustang hardtop . . . .

AUTOMOBILIA:

Fact, Fun & Fantasy -- Through Jan. 27 at the National Geographic Society, 17th and M streets NW. 202/857-7588. Open 9 to 5 Monday through Saturday and holidays and 10 to 5 Sundays. Metro: Farragut North, L Street exit. Good wheelchair access.