This is Volkswagen Testing Range in the vincinity of Wolfsburg.
Additional information from Bounkass:
This is Volkswagon’s highly secured test track. It has a restricted area no fly zone. About 22km long ( 17 miles ) and the longest stretch is about 9km ( 5½ miles ). This is also the track where Top Gear has tested the Bugatti Veyron at 407km/h ( 250mph ).