Just outside of Berlin is the "Heeresversuchsgelände Kummersdorf". This facility is still in use, and has hardly changed since the 19h century.
(period picture, source unknown)
Most impressive is the gradability hill. Each road up has it's own steepness, from 70% (35 degrees) to 10% (5.7 degrees). For safety al ramps have a winch, capable of securing even the heaviest tank, and pulling it uphill..
Close by is the "Verwindungsbahn" (distortion track) to rigidness and torque of vehicles.
(present day picture, 1990's of a vehicle rally, source unknown)
Present day picture of an OT-251, clearly showing the purpose of the track. The OT's front wheels are high up in the air. A good test for the driver too. If he drives too fast he crashes the front axle into the road.