Can an imitation ever beat the real thing?

That’s the question 4,000 vintage car collectors and fans will be asking this weekend when they travel to the Fairfield County Concours d’Elegance in Westport, Conn.

In addition to rare and expensive Duesenbergs, Delahayes, and Horches, they can also expect to see, if maybe not notice, a display of “artful dodgers,” or cars that are acknowledged to be reproductions: replicas, kit-cars, and out-and-out copies of classic car models.

Some of the “artful dodgers” were factory-sanctioned, built from original blueprints and nearly perfect in every detail. Others were made to order for a single collector. The Fairfield County Concours aims its high beams on an area that isn’t normally represented at an antique car show.

“The point is to show just how good reproduction cars can get,” the organizer of the show, Bill Scheffler, said. “These cars aren’t original, they aren’t what they purport to be, but they look and run so well that it’s hard to tell the difference.”

The popularity of reproduction cars touches on the paradox of antique car collecting: The rarer the car, the less likely it is to leave the garage. A Westport lawyer who co-founded the Fairfield County Concours five years ago, Mr. Scheffler said that reproduction automobiles are generally more affordable.

“Even though vintage racing is no-touch, well, touch happens,” he said. “You want to put your $1 million Ferrari on the track? Or do you want to fabricate an exactly identical car that isn’t sanctioned by the factory?”

Although he doesn’t race, Miles Morris, the former head of Christie’s international motor car department and a co-organizer of the concours, owns a late-1980s replica of one of three 1963 C-Type Jaguar XK120s built for the 24 Hour Le Mans race that year.

“My father actually owned one of the original C-Types, which I guess is why I’m interested in it. Not being in the multi-million-dollar bracket myself, that wasn’t going to happen in a hurry,” he said.

The engine, hydraulics, and running gear in the reproduction C-Type are old; the bodywork and the chassis frame are new. “It’s a 100% accurate replica,” Mr. Morris said. “If I changed the chassis plate with the one in the original car you probably couldn’t even tell them apart.”

Identical except for the price tag. Mr. Morris’s C-Type reproduction, which will be shown with the “artful dodgers,” cost $150,000. The original, he estimated, would cost more than $5 million.

Reproductions also don’t appreciate in value like the real thing. Lesser reproduction cars — a Ferrari 250 GTE turned into a replica of a Ferrari 250 Testa Rossa, to use one notorious example — depreciate as soon as you buy them.

“If you’re talking about a 1931 Cadillac V-16 Sports Phaeton that’s built on an old chassis but has reproduction coachwork, you’re probably talking about a car that’s worth half the real one,” the editor of Car Collector’s Market Journal, Rick Carey, said. “But if you’re talking about an Auburn Speedster replica made out of Tupperware on a Ford pickup truck chassis, of which there are many, you’re talking about a car that’s worth $125,000 out of the factory.”

Lynn Wilson, a former driver who raced at the 24 Hours of Daytona in 2004, owns a 1973 Porsche 911 RS. But the car, which will also appear with the “artful dodgers,” began its life as a lighter, less powerful, and less exciting Porsche 911 “T” Model also from that year. “For Porsche aficionados, the RS is a particularly attractive model,” Mr. Wilson said. “But they’re hard to find.”

“People that have these cars are the purist types who go out of their way to make sure that every screw is identical to the way it was when it rolled out of the factory,” Mr. Wilson, who owns a completely restored 1971 E Targa Porsche, said. “I’m sort of in between. For me, the car is functional.”

For the purists, 140 original classic cars and motorcycles will also be at the show, which is scheduled for Saturday and Sunday. Among them are such fabled pre-war designs as the 1928 Duesenberg Model J, the 1935 Delahaye 135, and the 1938 Horch 853A, the same car that won Best in Show at Pebble Beach in 2004.

That, and a 1958 Ferrari 250 Testa Rossa. One of 34 made, the sweptback red beauty, which is owned by Ralph Lauren, looks like it belongs in a museum. In fact, the Ferrari briefly resided at the Museum of Fine Arts, Boston, when Mr. Lauren’s car collection was exhibited there in 2005.

The Fairfield County Concours d’Elegance, Fairfield County Hunt Club, 174 Long Lots Rd., Westport, Conn. Tickets are $20 a person, or $40 a family.