Audi’s new A4 represents a looks-to-legroom redesign that packages some interesting technology—but the launch models only give a hint of things to come. Next year, Audi will introduce the hybrid version of the Q7 into series production, and the company is set to expand its hybrid option into other model ranges, including the A4. The Metroproject quattro design study (which foretells the Audi A1), revealed at the Tokyo Motor Show, also has a hybrid drivetrain.
Other companies are sharply focused on developing hybrids for high-volume compact cars. At Tokyo, Honda revealed plans to introduce an “affordable” global hybrid four-seat car that is slated to enter production in 2009.
While gasoline-electric systems lead the way into high-volume applications, diesel-electric solutions are also being taken seriously. A diesel-electric hybrid now under development by the Volkswagen Group looks likely to reach series production despite the technology’s associated cost penalty.
Although some form of hybrid drive is now de rigueur for companies (not least for public relations image reasons), the use of highly efficient diesels continues to provide convincing answers to CO2 emissions needs, particularly for high-performance cars.
A problem for companies such as Audi or Mercedes-Benz, which place great emphasis on their green credentials, is the production of very-high-performance gasoline-powered cars that put out large amounts of CO2 emissions.
Wolfgang Hatz, the VW Group’s Head of Powertrain Development, said that he had not experienced a negative attitude by the public to the 4.2-L 309-kW (414-hp) Audi R8, which achieves speeds of 301 km/h (187 mph) and produces CO2 emissions of 325 g/km. But he is aware that an alternative, lower-emissions power unit would be attractive in a social atmosphere of growing environmental awareness.
Could that mean a high-performance hybrid R8? Hatz was cautious in his reply: “I believe more in a diesel—not a hybrid diesel but just a diesel engine. An R8 diesel is my dream; we have to do power and ‘green.’”
The choice of engines could be wide. Audi’s most powerful current production V8 diesel is the 4.2-L, which produces 257 kW (345 hp) and 439 N·m (324 lb·ft). But also in the Audi diesel repertoire is a new V12 for the Q7 with 1000 N·m (738 lb·ft). Could it be shoehorned into the R8? Audi would neither confirm nor deny.
The VW Group also has the CCS (combined combustion system) research engine. Using a diesel block, it combines gasoline and diesel combustion systems but burns biofuel. Hatz does not see this technology as a replacement for gasoline or diesel engines but feels that it is more likely to be a third engine line when it enters series production. However, that may not happen for up to 10 years.
With a world car population of around 700 million and a yearly production of 60 million units, it would probably take four decades or more for a new technology to be thoroughly introduced to the global market, believes Hatz. “But we have learned some very interesting things from the CCS,” he said. “For example, cylinder pressure control via a sensor in the cylinder—and with HCCI [homogeneous-charge compression ignition] in the diesel mode, we have very low engine-out emissions and almost no NOx. What we must develop are combustion systems that self-clean—that do not need big filters.”
Although work on fuel cells continues within the VW Group, Hatz, like many leaders of technology development in the motor industry, is cautious about its prospects and regards its appearance in any volume as being at least 20 years away.
The efficient, low-emissions production of hydrogen remains a crucial issue, he said. Nuclear power is the likely production route at present; however, ecologically efficient volume production of hydrogen could still be 20 to 30 years away.
The most pressing strategic issue now is the further development of battery technology, said Hatz: “It is a trend that I really see coming on; it makes much more sense to do a total electric vehicle than a hybrid or fuel cell. But we have to be quick in achieving the level of battery technology required—certainly in less than 20 years—although the internal-combustion engine will then still be in use in several forms, burning various types of fuel.”