It was the best qualifying showing so far from the three-time DTM champion on his return to the series, having sat out the 2021 season, with Abt Audi driver beating Team Rosberg Audi rival Nico Muller to pole by 0.188s.
Thomas Preining completed the top three in his best DTM showing to date in the Team Bernhard Porsche, as Clemens Schmid was shuffled back from first to fourth in the final seconds of a frenetic qualifying.
After Ricardo Feller set the early benchmark time with a 1m41.323s, teammate Rast quickly asserted control of the session with a 1m40.687s followed by a 1m40.221s that third Abt driver Kelvin van der Linde came closest to matching with an effort that was 0.127s slower.
Schmid, who suffered a right-rear tyre blowout entering Tamburello in FP1 on Friday, was the best-placed of the Grasser Racing Lamborghini quartet in third at this point as team leader Mirko Bortolotti elected to remain in the garage until there were just six minutes remaining of the session.
But it was Schmid who stepped up to lead Lamborghini's charge with a 1m40.198s to snatch provisional pole, Bortolotti going 0.059s slower.
However, Rast then reclaimed the top spot with the only sub-1m40s lap of the session at 1m39.817s, with Muller and Preining also beating Schmid's time.
Another late effort from Feller split the two Grasser cars, leaving Bortolotti sixth-quickest, although the Italian will drop 10 places on the grid for running an incorrect set of tyres during FP2 that his team explained was caused by having the wrong tyre barcodes.
After a quick spin at Variante Alta, Kelvin van der Linde set the fastest middle sector of anybody on his final lap but it was good enough only for the seventh-quickest time.
But thanks to Bortolotti's penalty, he will start sixth, with double DTM champion Marco Wittmann the best of the BMW M4s starting seventh in his Walkenhorst Motorsport example.
Championship leader Sheldon van der Linde will carry 25kg from eighth on the grid in race one, after his victory last time out at the Lausitzring, with Mercedes drivers Lucas Auer (Winward) and Maro Engel (GruppeM) completing the top 10.
The two Red Bull Ferraris had a low-key outing in qualifying, with Nick Cassidy setting the 13th-quickest time and Felipe Fraga ending up further down in 24th.
DTM Imola - Saturday qualifying results:
| Cla | Nº | Driver | Car / Engine | Time | Delay |
|---|---|---|---|---|---|
| 1 | 33 | René Rast | Audi | 1'39.817 | |
| 2 | 51 | Nico Müller | Audi | 1'40.005 | 0.188 |
| 3 | 24 | Thomas Preining | Porsche | 1'40.039 | 0.222 |
| 4 | 85 | Clemens Schmid | Lamborghini | 1'40.121 | 0.304 |
| 5 | 7 | Ricardo Feller | Audi | 1'40.137 | 0.320 |
| 6 | 63 | Mirko Bortolotti | Lamborghini | 1'40.180 | 0.363 |
| 7 | 3 | K.van der Linde | Audi | 1'40.348 | 0.531 |
| 8 | 11 | Marco Wittmann | BMW | 1'40.409 | 0.592 |
| 9 | 31 | S.van der Linde | BMW | 1'40.431 | 0.614 |
| 10 | 22 | Lucas Auer | Mercedes | 1'40.474 | 0.657 |
| 11 | 88 | Maro Engel | Mercedes | 1'40.570 | 0.753 |
| 12 | 94 | Dennis Olsen | Porsche | 1'40.597 | 0.780 |
| 13 | 37 | Nick Cassidy | Ferrari | 1'40.626 | 0.809 |
| 14 | 19 | Rolf Ineichen | Lamborghini | 1'40.631 | 0.814 |
| 15 | 4 | Luca Stolz | Mercedes | 1'40.661 | 0.844 |
| 16 | 92 | Laurens Vanthoor | Porsche | 1'40.787 | 0.970 |
| 17 | 25 | Philipp Eng | BMW | 1'40.800 | 0.983 |
| 18 | 50 | Timo Glock | BMW | 1'40.927 | 1.110 |
| 19 | 36 | Arjun Maini | Mercedes | 1'40.935 | 1.118 |
| 20 | 1 | Maximilian Götz | Mercedes | 1'40.958 | 1.141 |
| 21 | 66 | Marius Zug | Audi | 1'41.063 | 1.246 |
| 22 | 55 | Mikaël Grenier | Mercedes | 1'41.127 | 1.310 |
| 23 | 18 | Maximilian Buhk | Mercedes | 1'41.301 | 1.484 |
| 24 | 74 | Felipe Fraga | Ferrari | 1'41.310 | 1.493 |
| 25 | 27 | David Schumacher | Mercedes | 1'41.392 | 1.575 |
| 26 | 12 | Dev Gore | Audi | 1'41.396 | 1.579 |
| 27 | 10 | Esteban Muth | BMW | 1'41.397 | 1.580 |
| 28 | 6 | Alessio Deledda | Lamborghini | 1'42.065 | 2.248 |
