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.”

Bosch’s concept car doesn’t go quite that far, but it does begin to rethink some of a car’s most basic operations. The brake and transmission controls are electronic rather than mechanical. The joystick isn’t meant to suggest that driving tomorrow’s cars will be like playing video games; rather, Bosch wanted a tangible demonstration of how multiple systems can be controlled in concert, by software. Move the joystick forward, and the car drives forward, as the trunk-bound PCs continually choose the optimum engine speed and transmission gear. Move it back, and a third element, the brakes, is also activated. The software saves three to five percent in fuel consumption over traditional operation via the gas pedal, brake pedal and gearshift, Kallenbach says.

A new software program means the same joystick provides Porsche-like acceleration and braking. Like the settings on your PC, the car’s parameters can be infinitely tuned. What’s more, video and radar inputs can tell of an approaching obstacle, allowing the computers to intervene and slow down before the driver does.

A second Bosch vehicle at the track, a modified Volkswagen Passat, demonstrates the networking concept at a deeper level, with one basic system: engine cooling. To prevent blown hoses or a warped engine block, today’s standard mechanical valves and belt-controlled water pumps keep a car’s engine in the 90 C to 95 C range. The rudimentary controls err on the safe side, keeping the engine protected but somewhat too cool for optimal fuel efficiency. But in the modified Passat, software-controlled valve actuators and an electric pump allow precise temperature control, setting the engine at 115 C at cruising speed or 90 C during hard acceleration or steep climbing, as reported by sensors elsewhere in the network. This thermal-management system can improve fuel economy by another two to five percent, says Kallenbach. And it can call the shots within the broader network, too. For example, when the engine is cold at ignition, the system could tell the transmission to use a lower gear, warming up the engine faster; a warm engine not only saves gas but emits less pollution and suffers less wear.

The same software principles extend to systems like air conditioning and could be used to manage steering-though that’s farther off due to the added risks that switching from mechanical to electronic controls would bring. Big jumps in fuel savings will come as more and more cars include “idle stop” functions (shutting down the engine at stoplights) and regenerative braking, in which braking force that would normally dissipate as friction-generated heat is captured to produce electricity.

Other experimental functions in Bosch’s digital car improve safety rather than efficiency. Its video and radar systems sense oncoming traffic and warn the driver if a collision is imminent, decelerate the car automatically, and could even intervene with future electronic steering systems.

Bosch, which invented the now ubiquitous antilock braking system, “is a leader in applying new electrical technologies to automobiles,” says Thomas Keim, an electrical engineer at MIT. “Eventually, everybody is going to have systems that work like this.”

But making these software visions a reality won’t be easy. To keep drivers safe, coordination software will need a backup-either a second, redundant system, or one that monitors the performance of the main software. Software controls must be cheap to build and install, standardized for many car models and simple to upgrade. They must also be far more reliable than typical desktop software-or as the industry takes steps toward greater software control and system integration, the phrase “car crash” will take on a maddening new meaning.

Despite the challenges, however, the era of the digital car is approaching too fast to stop.