Mercedes driver Robert Wickens topped the opening day of official DTM pre-season testing at Barcelona on Tuesday.
The Canadian set a best time of 1m06.735s among the 148 laps he completed in his HWA C-coupe during the afternoon, the test taking place on the short version of the circuit used for DTM events from 2006-09.
Wickens's car stopped on-track with a few minutes of the session remaining and was towed away. Mercedes has not revealed why.
Former champion Martin Tomczyk was second fastest in his BMW while Mercedes rookie Daniel Juncadella was third in his RSC Mucke car.
Mike Rockenfeller was the fastest driver in the morning and ended up fourth overall in the fastest of the Audi RS5s.
The German was driving the Phoenix car that his team-mate Miguel Molina will race this year while new Audi recruit Jamie Green was behind the wheel of Rockenfeller's regular car.
The spec DRS, which could be introduced this year, was evaluated by each of the three manufacturers, as was the definitive specification of the Hankook 'option' tyres, which have been refined continuously since their first tests last July.
The DRS was used on both straight and cornered sections of the circuit, but little or no overtaking simulations were attempted.
Champion Bruno Spengler said there was a marked difference with his BMW when the DRS, which mechanically flattens the rear wing plane by titling the entire assembly backwards, was activated.
"You clearly feel that you can change up earlier and that the top speed on the straights is higher," he said.
"That's something you have to accustom to and you have to focus on finding the limit lap by lap. Therefore, the test here at Barcelona - and the one in three weeks at Hockenheim too - are so important."
Pos Driver Car Time Gap
1. Robert Wickens Mercedes 1m06.735s
2. Martin Tomczyk BMW 1m06.787s + 0.052s
3. Daniel Juncadella Mercedes 1m06.857s + 0.122s
4. Mike Rockenfeller Audi 1m07.070s + 0.335s
5. Bruno Spengler BMW 1m07.100s + 0.365s
6. Gary Paffett Mercedes 1m07.374s + 0.639s
7. Jamie Green Audi 1m07.428s + 0.693s
8. Adrien Tambay Audi 1m07.536s + 0.801s
9. Augusto Farfus BMW 1m07.615s + 0.880s
10. Timo Glock BMW 1m07.909s + 1.174s
11. Filipe Albuquerque Audi 1m08.000s + 1.265s