European makers are on the leading edge of the industry's move toward "by-wire" technology, which uses electrical signals instead of mechanical and or hydraulic linkage -- for instance, in brake systems.
Controls for BMW's shift-by-wire are on the steering column
Both models will debut at the Frankfurt auto show in September, and U.S. sales are scheduled to begin next spring.
The next big advance will be steer-by-wire, but experts say it is still a few years away.
The technology offers noticeable customer benefits, said Reiner Emig, vice president of engineering for Robert Bosch Corp. in Farmington Hills, Mich.
With brake-by-wire, for instance, the brake pedal does not shudder when the antilock brakes engage, Emig said. Less obvious to the driver, brake-by-wire makes it possible for the system to identify an emergency braking situation based on driver input and apply more powerful braking automatically.
Mercedes' current brake-assist system is similar. Brake assist applies full braking pressure when sensors identify an emergency based on driver input. But brake assist is either on or off. In contrast, brake-by-wire will be on constantly.
"You are able to do things which would not be possible with the old mechanical linkage," Emig said. "You are not just replacing the linkage but also adding features."
Emig said throttle-by-wire has been in use since the early 1990s in V-12 engines. The system reduces emissions greatly during a cold start, he said.
"We predict the technology will be in close to 100 percent (of all engines) in the medium term," he said.
Rival Continental Teves also is working on by-wire systems, said Phil Headley, chief engineer, advanced technologies for Continental Teves North America in Auburn Hills, Mich.
A couple of things have happened to drive the technology, he said.
"One is that computers have gotten a lot less expensive. At the same time, they have become a lot more durable and able to live in a vehicle environment. And people have just gotten more comfortable with them, and confident."