Fully autonomous vehicles are still several years in the future, but the enabling technologies are increasingly appearing in today's cars. One example is the use of satellite based location and terrain mapping data in controlling vehicle systems. +BMW and other manufacturers have talked for some time about this kind of integration. 

If the car knows can look far enough down the road beyond the driver's sight-lines, it can make control decisions about managing things like the throttle, transmission, brakes and other systems to optimize fuel efficiency by avoiding acceleration or a down-shift right before you crest a hill or allowing the cruise control to dissipate speed before going into a corner. It should be very interesting to see how well this first generation control system works out.