A few mysterious cars grace the parking lot of the Bosch test track, about 100 kilometers northeast of Stuttgart, Germany. Most are next year's body styles, fenders shielded by foam panels and tape to thwart nosy competitors or journalists. But perhaps the most radical prototype is the most outwardly prosaic: a midnight blue Audi station wagon. Closer inspection reveals computers stuffed into its trunk, a joystick grafted onto its center console, a video camera glued to the windshield and a radar antenna bulging from a hole sawed in the front grill.

The digital auto provides a glimpse into a future where vehicle systems like brakes and transmission are electronic, software-controlled and, above all, networked with each other and with the outside world. "To put it very simply, you are turning the car into a computer," says Rainer Kallenbach, general manager of the group that modified the prototype for Bosch, a major auto industry supplier based in Stuttgart. By contrast, the systems in today's cars "have limited communication and are not jointly operated," which also limits their efficiency, Kallenbach says.

Bosch's so-called Cartronic software can fine-tune braking and downshifting, optimize engine temperature and manage the generation and consumption of electricity. The company plans to bring the technology to market as early as 2005, and its work is expected to lead, eventually, to safer, peppier, 30-kilometers-per-liter (80-miles-per-gallon) cars that still use internal-combustion engines yet emit little more than carbon dioxide and water.

The continually decreasing cost of the underlying microprocessors and other components-combined with competition among automakers and major auto suppliers-means automotive systems like Bosch's will roll steadily into the marketplace over the next decade, starting with high-end models, according to Lino Guzzella, codirector of the Measurement and Control Lab at the Swiss Federal Institute of Technology in Zrich, which tests and develops engine control systems. "This is where the future is for everybody in this business," Guzzella says. "Fuel consumption can still be cut in half, and emissions can be zero."