...AND CHEAPER...:

"My opinion is it's a bridge too far to go to fully autonomous cars," Mr Musk said in an interview with the Financial Times. "It's incredibly hard to get the last few per cent [of miles driven]."

But automating 90 percent of miles driven is possible within three years, Musk said, declining to offer specific details on Tesla's plans. 

It's a step towards reducing the inefficiencies of imperfect human pilots. Drivers have a tendency to accelerate too quickly, brake too hard, and jam together in bottlenecks that are as grating on cars as they are on commuters. Driverless cars would optimize traffic with the aid of sensors, data, and algorithms, the theory goes, getting people from point A to B with fewer traffic jams, fewer starts and stops, and thus less energy use.  

In 2011 alone, Americans lost 4.8 billion hours, 1.9 billion gallons of fuel, and $101 billion in delay and fuel costs due to traffic congestion, according to the Texas Transportation Institute.

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