BMW Andretti driver Maximillian Gunther topped the times on the first morning of Formula E pre-season testing at Valencia, while Mercedes encountered a technical problem on Nyck de Vries's car.
Gunther's best time - a 1m15.926s set on his final lap of the morning session - was 1.051 seconds quicker than the fastest time from last year's pre-season test, a 1m16.977s posted by his BMW predecessor Antonio Felix da Costa.
After Tuesday morning's initial laps were dedicated to installation running, Porsche's Andre Lotterer moved to the head of the times with a 1m16.650s.
Lotterer stayed first until just past the halfway mark of the three-hour session, when he was deposed by Gunther's effort of 1m16.228s.
Reigning FE champion Jean-Eric Vergne then moved to the top of the order on a 1m16.193s as most of the field began to set times quicker than the 2018 benchmark.
Da Costa replaced new team-mate Vergne in first towards the end of the morning with a time of 1m16.032s on a lap that featured a significant improvement in the final sector.
But Gunther took top spot away from da Costa just after the chequered flag had fallen, to lead by 0.106s heading into the two-hour lunch break.
Behind the DS Techeetah drivers were Nissan e.dams pair Oliver Rowland and Sebastien Buemi, with the Japanese manufacturer's cars sporting an all-black testing livery.
Audi's Lucas di Grassi was sixth, ahead of Pascal Wehrlein (Mahindra Racing) and Dragon driver Nico Mulller.
Mitch Evans (Jaguar) and Venturi's Edoardo Mortara rounded out the top 10.
Lotterer ended up 12th with a best time of 1m16.622s.
The morning running was interrupted by three red flags - the first of which was caused by new Jaguar recruit James Calado hitting the wall at the chicane on the start/finish straight after just 20 minutes.
Calado went on to finish the morning running in 21st place.
The middle stoppage was caused by de Vries stopping his Mercedes at the left-hand Turn 10 kink at the far side of the circuit at the start of the second hour.
It took more than 15 minutes for the 2019 Formula 2 champion's car to be recovered, after which he did not return to the track and was classified in 23rd place - three places behind team-mate Stoffel Vandoorne.
A Mercedes spokesperson told Autosport that a technical issue resulted in a blown battery fuse, which caused de Vries to pull over.
Mercedes is investigating the issue and is changing the necessary components so de Vries can drive again in the afternoon.
The final red flag occurred 20 minutes before the lunchbreak when Porsche's Neel Jani, who was classified in P19, stopped at the pit exit.
Tuesday morning times
|2||Antonio Felix da Costa||DS Techeetah||DS||0.106s||27|
|3||Jean-Eric Vergne||DS Techeetah||DS||0.236s||37|
|6||Lucas di Grassi||Audi||Audi||0.371s||28|
|22||Ma Qing Hua||NIO||NIO||4.645s||19|
|23||Nyck de Vries||Mercedes||Mercedes||6.574s||13|