Lewis Hamilton confirmed that he was feeling much happier about the new Mercedes than he was with last year's model, after he came out on top of Thursday's second practice session for the Bahrain Grand Prix.
"I'm feeling much happier with the car than last year," he said after the end of the one hour practice. "We've made some good improvements and it feels much more like a race car.
"It's a really good platform for us to build from, we just need to keep our heads down and keep chasing," he added.
Hamilton's best time of 1:30.374s was two tenths quicker than his team mate George Russell, followed by Aston Martin's Fernando Alonso and Ferrari's Carlos Sainz.
Red Bull's Max Verstappen remains favourite to win this weekend's season opener despite being only P6 in today's evening session, almost half a second slower than Hamilton.
"The car was feeling good but we can't get ahead of ourselves," cautioned Hamilton. "We didn't know exactly where we would stack up against everyone else, but we had a positive FP2
"We know there is more to extract, and our long run pace isn't in the fight with the Red Bulls," he added.
That sentiment was shared by Russell," who said: We're not going to get carried away after one day of practice.
"Our qualifying pace did look strong, but ultimately our long run pace is where it counts. Verstappen looked comfortably quickest, and it was very tight with the Ferraris, the McLarens, and the Aston Martins.
"We've likely got a real fight on our hands there," he suggested.
"Nevertheless, we're pleased with how our day has gone; the car is performing well. We will sit down and understand where the main improvements came from and try to sustain that. We want to be fighting for good positions on Saturday."
Mercedes' trackside engineering director Andrew Shovelin admitted that after last week's three-day official pre-season test at Bahrain International Circuit, the team had been most concerned about its single lap pace.
"We had both drivers in the simulator before returning here," he revealed. "From the running today, it looks like we have improved.
"We're certainly not getting carried away, as there is plenty of scope within power unit modes and fuel loads for several cars to find a chunk of time before tomorrow but it's encouraging that the picture we had last week seems to have improved.
"The long run data also looks close," he added. "Verstappen is still comfortably out front, as we saw last week, but behind him it's going to be a tight battle for the remaining podium spots.
"We know we've got plenty to fine tune on the balance. It's still early days with the W15 and we're learning how to get lap-time out of it. But it's already feeling very different to the last two years that we have been here."
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