MUNICH — Only weeks before the launch of Audi's first CVT, the debate about the future of the continuously variable transmission continues to stir controversy.

BMW AG and DaimlerChrysler AG's Mercedes-Benz are yet to be persuaded that CVT represents the future of automatic transmissions for big engines, despite admitting intense interest from all the major European automakers.

“We are not convinced about the CVT from the point of view of cost,” says Burkhard Goschel, the BMW engineer who heads general vehicle design and innovation. “We can see competition (for CVTs) from Selespeed systems, where the manual gearbox provides an automatic mode. Automatic manuals maybe a better solution.”

Nor does Goschel think automakers are remotely close to writing the obituary for the normal hydraulic automatic gearbox. “Conventional automatics are getting better all the time, in terms of shift quality and efficiency,” he says.

“Five-speeds could become six, especially for diesels, with their resisted rev range. We see a future for CVT with small engines. We already have a CVT on some of our small Rovers and now the MGF. They work best with transverse engines and front-wheel drive. In this, I think Mercedes-Benz thinks the same way as BMW.”

Even Franz-Josef Paefgen, the boss of Audi, who is only weeks away from launching the A6 2.8 with a CVT, admits nobody knows how successful the concept will be of a CVT behind a large capacity engine.

Until the launch of the new Nissan Primera, CVTs had been limited to engines of around 1.6L with maximum torque of around 135 Nm (100 ft.-lbs.). The 2L Primera with CVT pumps out 180 Nm (133 ft.-lbs.). Audi intends to lift this to the 279 Nm (206 ft.-lbs.) of its 193-hp 2.8L V-6.

“It's a small first step,” Paefgen says. “We have no idea of the acceptance level of our customers.

Despite the sophisticated electronics, there is still a different feeling when driving a CVT. In a year, we will know more. We are at the end of a long development and investment period and the numbers will be small at first.

Five years down the road time, Paefgen says, he expects that 50% of cars with automatic transmissions will be CVTs. By then, CVTs will be capable of coping with about 339 Nm (250 ft.-lbs.). “Even today,” he says, “we think the CVT can be in the same range of performance and economy as a manual gearbox, and far ahead of a normal automatic.”

Paefgen says Audi's CVT, developed in-house in Ingolstadt, inevitably will be offered to other brands within the VW Group. “It will be available for interested users, but I can't see others (rivals) buying it for the moment.”

The first is expected to be VW with the Passat V-6, which shares its drivetrain with the A6. However, the numbers of CVT produced in VW's Kassel gearbox plant are going to be small, around 10,000 in the first year, a VW source says.

The limiting factor for CVTs, up to now, has been finding a belt design capable of transmitting torque without slipping. Audi is believed to have developed a new type of belt with a still-secret supplier that overcomes this limitation.

“CVT is the transmission of the future,” say Wolfgang Reitzle, the former head of development at BMW, and now boss of Ford Motor Co.'s Premier Automotive Group. “It's only a question of time,”