Audi's long-distance piloted-driving test started Sunday in Silicon Valley (Photo: Audi)

Audi is taking journalists on a 550 mile test of its "piloted driving" technology, demonstrating how much progress the industry is making in its efforts to let systems take over at least some of the driver's activities.

The German premium brand, part of the Volkswagen Group, has been pushing hard to make the move from advanced driver assistance to what it calls piloted driving. The test, which started Sunday in California, follows a similar but shorter drive Mercedes made with an autonomous S Class on a 100 km route in 2013.

Audi's long-distance test drive, which takes place in normal traffic conditions on regular roads, involves an A7 Sportback concept car on a route from Silicon Valley to Las Vegas, where the annual international CES electronics fair starts later this week.

The A7 concept can take over a driver's duties at speeds of up to 70 mph. It accelerates, brakes, changes lanes and passes other cars autonomously, using a combination of sensors that mostly are ready for production.