SSR Performance driver Olsen lapped the Portuguese circuit in 1m41.375s, usurping Abt Audi driver Ricardo Feller’s benchmark from Tuesday by just over two tenths of a second.
It ended Audi’s unbeaten streak in pre-season testing, with the Ingolstadt-based manufacturer having also topped the opening two days of testing in Hockenheim earlier this month.
Second-quickest on Wednesday was the Team Rosberg Audi of Muller, who ended up 0.269s off the pace with a time of 1m41.697s.
The Swiss driver narrowly edged out the top Lamborghini of Nick Thiim, who continued his impressive form in pre-season testing to finish third for the T3 Motorsport team.
Feller couldn’t match his chart-topping time from Tuesday but still ended up a respectable fourth on the timesheets, just ahead of the Team Bernhard 75 Porsche of Thomas Preining.
Factory Lamborghini driver Mirko Bortolotti ended the day sixth quickest for the Grasser Racing Team, just ahead of his Porsche counterpart Laurens Vanthoor in the second of the two SSR Performance cars.
HRT’s new recruit Luca Stolz was the top Mercedes representative in eighth, half a second off the pace of Olsen, while the top 10 was rounded by the lead BMW of Sheldon van der Linde (Schubert) and Mercedes driver Mikael Greiner (GruppeM).
Red Bull driver Felipe Fraga posted a time of 1m42.005s to end the day 11th quickest in his AF Corse Ferrari, just ahead of the Abt Audi of three-time DTM champion Rene Rast.
Fraga’s team-mate and WRC legend Sebastien Loeb completed a full day of running for the first time in pre-season testing, logging 75 laps in his AlphaTauri-liveried Ferrari ahead of his DTM debut later this weekend at Portimao.
Loeb’s best time was a 1m42.990s which put him 28th on the timesheets, just ahead of T3 Motorsport’s Esmee Hawkey and GRT rookie Alessio Deledda.
British driver Ben Green again joined the 29-car field as a reward for winning the GT4-based DTM Trophy last year, finishing just ahead of Loeb in 27th position.
Wednesday’s test again ran late in the evening to allow the DTM to complete TV construction work in daylight, although all drivers returned to the pits by 9pm - an hour before the official end of the day’s running.
There was also a disruption earlier in the day around 6pm when Marco Wittmann crashed his Walkenhorst BMW at Turn 6 with what the team suspects to be a technical problem.
The two-time DTM champion didn’t venture out on track again after the incident as the squad investigated the issue in detail, leaving him 19th in the classification with just 16 laps on board.
DTM Portimao test - Day 2 results:
| Pos | Driver | Team | Time | Gap |
|---|---|---|---|---|
| 1 | Dennis OLSEN | SSR Performance | 1:41.378 | - |
| 2 | Nico MULLER | Team Rosberg | 1:41.647 | +0.269 |
| 3 | T3 Motorsport | 1:41.690 | +0.312 | |
| 4 | Ricardo FELLER | ABT Sportsline | 1:41.721 | +0.343 |
| 5 | Thomas PREINING | KÜS Team Bernhard | 1:41.742 | +0.364 |
| 6 | Mirko BORTOLOTTI | GRT | 1:41.771 | +0.393 |
| 7 | Laurens VANTHOOR | SSR Performance | 1:41.822 | +0.444 |
| 8 | Luca STOLZ | Mercedes-AMG Team HRT | 1:41.926 | +0.548 |
| 9 | Sheldon VAN DER LINDE | 1:41.971 | +0.593 | |
| 10 | Mikael GRENIER | Mercedes-AMG Team GruppeM | 1:42.001 | +0.623 |
| 11 | Felipe FRAGA | Red Bull AF Corse | 1:42.005 | +0.627 |
| 12 | Rene RAST | 1:42.023 | +0.645 | |
| 13 | Maximilian GOTZ | Mercedes-AMG Team WINWARD | 1:42.042 | +0.664 |
| 14 | ABT Sportsline | 1:42.079 | +0.701 | |
| 15 | Mercedes-AMG Team WINWARD | 1:42.093 | +0.715 | |
| 16 | 1:42.094 | +0.716 | ||
| 17 | Mercedes-AMG Team Mücke | 1:42.106 | +0.728 | |
| 18 | Mercedes-AMG Team HRT | 1:42.121 | +0.743 | |
| 19 | Marco WITTMANN | 1:42.167 | +0.789 | |
| 20 | Schubert Motorsport | 1:42.252 | +0.874 | |
| 21 | David SCHUMACHER | Mercedes-AMG Team WINWARD | 1:42.321 | +0.943 |
| 22 | Team Rosberg | 1:42.323 | +0.945 | |
| 23 | GRT | 1:42.366 | +0.988 | |
| 24 | GRT grasser-racing.com | 1:42.401 | +1.023 | |
| 25 | Walkenhorst Motorsport | 1:42.541 | +1.163 | |
| 26 | Mercedes-AMG Team GruppeM | 1:42.595 | +1.217 | |
| 27 | Ben GREEN | Mercedes-AMG Team HRT | 1:42.909 | +1.531 |
| 28 | Sebastien LOEB | AlphaTauri AF Corse | 1:42.990 | +1.612 |
| 29 | Esmee HAWKEY | T3 Motorsport | 1:43.040 | +1.662 |
| 30 | Alessio DELEDDA | GRT grasser-racing.com | 1:43.774 | +2.396 |
