Having already won the penultimate race of the season on Saturday to stretch his advantage to 27 points, Preining wrapped up the title in qualifying on Sunday after beating his title rival Mirko Bortolotti to pole position by 0.006s.
It gives him an unassailable 28-point lead in the standings, with only 25 on offer in the final race later in the afternoon.
Bortolotti needed to qualify on the front row and hope Preining set a lap that was no faster than fourth in order to remain in the hunt for the championship.
The Lamborghini driver set the fastest lap of the weekend on his first attempt, a 1m37.016s, before underlining his credentials with a blistering time of 1m36.806ss to consolidate his position at the top.
But Preining managed to go even quicker with just two minutes left in qualifying to end Bortolotti's title hopes, his time of 1m36.800s clinching him pole position for a second day in a row - and adding three crucial points to his tally.
The result makes him the first Porsche driver to win the DTM title, and only in the second year of the German manufacturer’s participation in the series.
Source: Autosport