The Volkswagen Golf—or VW Rabbit, as it’s known in North America—may be the most flexible and widely used car in the world. Not the car itself—it’s a very good five-door hatchback, the kind Europeans love and Americans ignore—but because its underlying architecture has spawned a phenomenal volume of other cars. The Golf’s underpinnings are used in more than 3 million cars a year, sold under the Volkswagen, Audi, Seat, and Skoda brands.

Now, as VW gets ready to unveil the sixth generation Golf at next month’s Paris Auto Show, the company will reveal a plug-in hybrid concept. If it goes into production, the hybrid would make the Golf Mk VI the only car in the world offering gasoline, diesel, and hybrid powertrains in the same vehicle.

The TwinDrive plug-in hybrid concept, first revealed in June, is being tested in up to 20 present-generation Golfs. A lithium ion battery pack powers the car for up to 30 miles of electric range, with a combustion engine kicking in after that. This arrangement is similar to that of the Chevrolet Volt, which GM calls an “extended-range electric vehicle,” rather than a “power-split hybrid” system—like those used by Toyota.

The Golf TwinDrive has been adapted to plug in to wall current to recharge its battery pack. Earlier this year, VW also showed a TDI diesel hybrid concept—but without a plug.

Alongside the TwinDrive concept, the Golf Mk VI will be launched with a remarkable range of powertrain alternatives. VW offers engines with gasoline direct injection, turbo diesels, and its unique 1.4-liter “TwinForce” TSI engine, which is both supercharged (at low revs) and turbocharged (at high revs.) The lowest-consumption BlueMotion diesel version gives roughly 62 miles per US gallon, with CO2 emissions of just 99 g/km—similar to ultra-economy cars a whole size smaller, like Ford’s Fiesta ECOmotion.

Meanwhile, Volkswagen now offers the current Rabbit (Golf Mk V), Jetta sedan, and Jetta Sportwagen models in the US with a 2.0-liter turbocharged TDI diesel that complies with emissions and safety standards in all 50 states.

First launched in May 1974, the Golf was the car that saved Volkswagen. That company’s Beetles had done spectacularly well in the 1950s and 1960s, but by the early 1970s, it was clear that rear-engine, air-cooled volume cars could never meet upcoming emissions and safety standards. The first Golf, crisply styled by Guigiaro, was as modern as any Euro-hatch, with a water-cooled, transverse engine driving the front wheels, enormous space inside, and tight German handling. Renamed the Rabbit for the US market, it confirmed the basic design for a small car—transverse engine up front, driving the front wheels—a feature pioneered by long-extinct British makes during the 1960s.

Three and a half decades later, VW has sold 26 million Golfs in five generations. The latest one has been simplified under the skin to reduce its build cost, but offers greatly reduced wind noise and better interior fittings nonetheless. North America isn’t likely to see the Golf (or Rabbit) Mk VI until 2010 though, as VW customarily lags a year behind the European launch in other markets.