ZF North America president Julio Caspari told US industry journal Automotive News he is unsure if the potential fuel efficiency gains achievable by adding more ratios to auto gearboxes are great enough to justify their significant development and production costs.
"We are coming close to the limit," Caspari said. "Can we produce a perfect transmission, and what would it cost? We would need to look at things like ceramic ball bearings to reduce friction, which would be expensive."
Caspari said there was only an 11 per cent gap between the theoretical ‘perfect transmission’ and the most efficient transmissions on the market today.
ZF began producing its eight-speed automatic transmissions for vehicles with longitudinally mounted engines in 2009, which it says leads to 11 per cent better fuel economy than a standard six-speed auto. ZF’s eight-speed auto is used by a number of luxury European car makers including Audi, Bentley, BMW, Jaguar Land Rover, Rolls-Royce and Volkswagen, as well as Chrysler and Dodge.
Next year, it will begin production of a nine-speed automatic unit designed for vehicles with transverse-mounted engines, which claims to be 16 per cent more efficient than a six-speed. Chrysler is the first manufacturer to get on board, and plans to roll out the nine-speed across its entire front-wheel-drive line-up over time.
Caspari was unflustered by reports that Hyundai is developing a 10-speed automatic transmission for use in its high-end Genesis and Equus models from 2014, suggesting that time will tell if the extra ratio will make real-world economy improvements or prove to be little more than a marketing exercise.
Caspari would not comment on whether ZF was developing its own 10-speed transmission, and said the company’s next major project was an upgrade to its eight-speed unit.