FORTUNE -- News item: A four-door model will be joining the lineup of Bugatti, the maker of world's fastest production car. Volkswagen AG, Bugatti's corporate parent, has given the go-ahead to build the 16C Galibier sedan, which has a 1,000 horsepower engine, a top speed of approximately 220 miles per hour, and will cost about $1.4 million.
This is no April Fool's joke. The fever to add two more doors to some of the world's most iconic sports cars has apparently reached epidemic proportions. Bugatti, maker of the super-fast, super-expensive Veyron, has been teasing cognoscenti with the Galibier since its unveiling at a private showing during the Frankfurt auto show in September, 2009. The project was presumably put on hold while Europe and North America recovered from the financial crisis, but Bugatti has been leaking photos in the interim and now appears ready to go ahead. (For those not in the know, the Col du Galibier is a mountain pass in the southern region of the French Alps that is often the highest point of the Tour de France. Despite the origin of their founder, who was born in Milan, Bugattis have always been built in France).
Bugatti's move to add a family-friendly model to its heretofore exclusively sports car lineup follows on the heels of two other European manufacturers who previously specialized in two-door and two-seat cars.
In September, 2009, Porsche introduced the four-door Panamera at a starting price of $90,750. (The top-of-the-line Turbo starts at $133,550). Despite its somewhat ungainly appearance -- not to mention its punishing price tag -- the Panamera has gone on to become Porsche's most popular car, outselling the two-door 911.
Right on Porsche's heels was the Aston Martin Rapide, a four-door interpretation of the DB9 that carried an even more elevated MSRP of $199,950. Like the Panamera, the Rapide has a fifth door in the rear for the loading of golf bags and other impedimenta. Unlike the Porsche, which has the rear-seat legroom of a limousine, the aft seating compartment of the Aston is best accessed by contortionists.
The addition of four-doors to the offerings of traditional sports car makers has antagonized purists, many of the same ones who complained loudly when General Motors had the temerity to put the "GTO" label, heretofore reserved for coupes, on a Pontiac four-door. One of the most vociferous has been Peter DeLorenzo, author of the popular Detroit blog AutoExtremist. The Panamera, he wrote, "marks the end of the historical legacy that once forged the reputation of Porsche, it's a blatant repudiation of everything that its founder once stood for."
But then purists have been complaining ever since sports car makers replaced side curtains with rollup windows and started offering air conditioning and automatic transmissions. Marketers would say that in adding four-doors to a sports car marque is merely a case of brand extension. From a practical point of view, much is gained in functionality while little is lost in performance, appearance, or panache. The cars remain breathtakingly exclusive. Aston Martin figures to sell 2,000 Rapides annually worldwide, while only about 50 Bugattis see the light of day each year. Some of those drive straight into private collections without ever turning a wheel on a public road.
Some of the complaints had their origin in automotive history. Back in the day, only frumpy family sedans had four doors, while two-door coupes, with their stiffer body structures and more graceful lines, were considered the peak performers and were consequently more appealing to the sporting set.
That began to change in 1968 with the introduction of the BMW 2002. With a fully independent suspension, McPherson struts, and front disc brakes, it was the first sedan-bodied car with sporty aspirations.
Now Ferrari and Lamborghini are the last two-door holdouts, and Ferrari has begun adding two more seats to its more recent models in an apparent bow to functionality.
For 2011, Mini is following the trend by launching its first four-door, the Countryman. Though nicely styled and still less than fourteen feet long, its new configuration got a thumbs down from Wall Street Journal reviewer Dan Neil because of its additional apertures. "At the risk of being puritanical, it seems to me that sometimes car companies have to walk away from the short-term expedience of a few thousand sales, or even a few tens of thousands of sales, to protect the meaning, the truth, the inner logic of a brand," Neil wrote. "Mini has spent years selling itself as automotive counter-programming, and now it's acting like every other car maker with white space to fill."
In fact, the heated discussion over two-doors vs. four massy be serving as a prelude to the debate over a more consequential topic: future successors to the gasoline engine. Already, the traditionalists are in a tizzy over the hybrid Porsche, which they view as a dangerous departure from internal combustion. Wait until they see the battery-powered, all-electric Rolls Royce.