Jamie Green put Audi at the head of the times on the third day of DTM testing at Barcelona.
The Briton, who ended an eight-year stint with Mercedes in the DTM to switch to Audi late last year, completed 180 laps of the Spanish circuit and recorded a best time of 1m07.171s, putting him a scant 0.065sec clear of the pack.
"It was a good day," Green said. "We went through our plan and did everything we had on today's checklist, so that's a pretty good thing.
"The track was dry, there were no interruptions, no technical problems and we did a lot of laps – over 100 in the afternoon, and this is all helping me to get a feel for my new RS5 and to help me gel with my engineers."
DTM rookie Pascal Wehrlein, a race winner in the Formula 3 European Championship at Monza last weekend, was second fastest in what was his first outing for Mercedes since being confirmed as Ralf Schumacher's replacement at the RSC Mucke squad.
Morning pacesetter Filipe Albuquerque was third fastest for Audi with Roberto Merhi fourth for Mercedes and within a tenth of a second of Green's benchmark time.
On what was the closest day of the test in terms of times, less than 0.6sec covered the 11 drivers that took to the track. Slowest was BMW rookie Marco Wittmann.
The test concludes on Friday.
Pos Driver Car Time Gap
1. Jamie Green Audi 1m07.171s
2. Pascal Wehrlein Mercedes 1m07.236s + 0.065s
3. Filipe Albuquerque Audi 1m07.257s + 0.086s
4. Roberto Merhi Mercedes 1m07.266s + 0.095s
5. Adrien Tambay Audi 1m07.274s + 0.103s
6. Christian Vietoris Mercedes 1m07.309s + 0.138s
7. Dirk Werner BMW 1m07.413s + 0.242s
8. Mike Rockenfeller Audi 1m07.463s + 0.292s
9. Andy Priaulx BMW 1m07.590s + 0.419s
10. Joey Hand BMW 1m07.594s + 0.423s
11. Marco Wittmann BMW 1m07.742s + 0.571s