The six cars include both HTP Motorsport cars, including the pole-sitting No. 85 entry and the No. 00 Black Falcon car piloted by Maro Engel and Bernd Schneider.
The stewards confirmed the penalties just over four hours before the start of the race.
All six cars have had their Superpole times deleted, relegating them to positions 15-20 on the grid.
All cars will then have to serve a five-minute stop and go penalty during the race, effectively ensuring that all six cars will spend two full laps parked in the pits.
The heavy penalties were just the last to be handed out after the Superpole session, elevating the No. 28 WRT Audi of Vanthoor, Rast and Muller to pole position.
Initial top qualifier Maximilian Gotz lost pole position when he was judged to have set his fastest time while racing through a yellow flag zone for the stopped McLaren of Shane van Gisbergen.
The eighth-fastest car, the No. 74 ISR Audi, lost both its Superpole laps after driver Franck Perera was judged to have exceeded track limits on both timed laps.
Two further cars, the No. 89 Mercedes and the No. 38 Lamborghini will start from pit lane after engine changes.
Although a final grid has yet to be published, the penalties should move Van Gisbergen’s McLaren to 13th on the grid.
Van Gisbergen initially sat at the foot of the times after the two-lap session for the 20 fastest cars after qualifying, his McLaren rolling to a stop before he could complete a flying lap.
“The #58 was stopped as a precautionary measure in sector 2 of its first flying lap during the Superpole session,” a statement from the Garage 59 team read.
“Van Gisbergen had shown strong pace in the opening sector but an anomaly was noticed by the team in the garage and the decision was made to stop the car to ensure no damage or issues ahead of tomorrow’s race.”
The No. 58 appeared to run faultlessly throughout the 10-minute warm up session. A steady run from co-driver Rob Bell setting the 46th-quickest time, the British driver also entrusted to drive the opening stint in the race.