Self-driving cars are expected to increase road safety, and free up at least some time for their occupants during the morning commute.

Machines will never get distracted--eliminating the cause of many crashes--and it appears they have other talents as well.

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Porsche is testing a semi-autonomous system called InnoDrive that promises to be more efficient than a human driver--and it turns out that it's faster, too.

That's the judgment of Yahoo! Autos after a writer went for a spin in a Porsche test vehicle equipped with the system.

Based on Porsche's adaptive cruise control and fitted to a Panamera Turbo sedan, the system adds satellite-derived terrain and traffic information, as well as input from additional cameras, radar, and other sensors to get a complete picture of the environment.

2014 Porsche Panamera Turbo S

2014 Porsche Panamera Turbo S

InnoDrive controls the throttle and brakes, but a human is still needed to steer and select one of three driving modes--efficient, comfort, or dynamic.

Once engaged, the system tailors control inputs to each of the three modes, maximizing fuel efficiency in efficient mode, minimizing harsh g-forces in comfort, and going for maximum velocity in dynamic mode--without breaking the speed limit, of course.

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It does this by using stored and sensor-generated to data to "predict" conditions ahead, anticipating when to apply brakes, use the throttle, or let the car coast.

Engineers say slowing down doesn't help efficiency, so the system is programmed to go around corners as fast as possible. This is Porsche, after all.

In testing, Porsche found InnoDrive to be 10 percent more efficient than a human driver, as well as 2 percent faster.

Don't throw out your driver's license just yet, though.

2014 Porsche Panamera first drive

2014 Porsche Panamera first drive

An InnoDrive-equipped car can only "see" to a distance of 200 meters (about 650 feet) directly ahead of it, and it can't differentiate between red and green traffic lights yet--it assumes they're all green.

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These limitations echo those of other autonomous systems demonstrated so far, but carmakers believe such technology will eventually have a place in showrooms.

Porsche's corporate cousin Audi is expected to launch a system that will autonomously pilot cars through traffic jams in 2016.

Similarly, Tesla Motors introduced an "Autopilot" for its Model S electric car last month, and claimed it could serve as the foundation for increased vehicular autonomy.


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