MONTMELO, Spain (AP) New rules. New cars. Same result.
Mercedes dominated the first day of Formula One preseason testing on Monday, sending a message that the overhaul of regulations may not derail the three-time defending champion.
While Lewis Hamliton aimed for speed, new teammate Valtteri Bottas went for distance as they shared time behind the wheel of the revamped Silver Arrow.
Hamilton took over driving in the afternoon and clocked the day's fastest lap, bettering Sebastian Vettel in his Ferrari by 0.113 seconds.
''We are still the team to beat,'' Hamilton said, before adding that he loved the new, faster car.
''It is a beast. It's a much more beefed up version of the car that we had in recent years.''
In four hours of driving before lunch, Bottas outworked the rest of the field with 79 laps at the Circuit de Barcelona-Catalunya. That total surpassed the 66 laps of the Spanish Grand Prix at the same venue.
Only Vettel and Felipe Massa ended up with more laps, but that was in double the time following the entire eight-hour session.
''It's a great feeling,'' Bottas said after his maiden run in the Mercedes. ''(The engineers) did an amazing job in the winter. I only started a month ago, but what I have seen has been very impressive. For us, the main thing is to get the mileage now.''
Bottas inherited the driver's seat at Mercedes from world champion Nico Rosberg, who retired in December five days after clinching the title.
The Finn said he planned to have a more constructive relationship with Hamilton than his predecessor, who openly sparred with Hamilton as they dueled for the past three driver's titles in the absence of a real threat from other teams.
''I am sure that we are going to share every little bit to help the team go forward and I see no reason for any issues in the future,'' Bottas said. ''I don't think there will be a No. 1 or a No. 2 on the team. We both will be driving for our own results, but for the team we need to work well as a good pair of teammates.''
Mercedes' rivals are hoping the regulation changes will help them make up ground on a team that has won 51 of the last 59 races.
Other than Vettel's positive showing, there was little sign that the gap had closed.
While Hamilton and Bottas took turns churning out the laps under sunny and dry conditions, McLaren and Red Bull endured inauspicious starts.
Fernando Alonso's McLaren was stuck in the garage for hours following a sole trip around the track as its technicians repaired an oil-related problem with its Honda motor.
Red Bull driver Daniel Ricciardo didn't do much better, needing to be ferried back after just four laps when his new RB13 ground to a halt. Once the team repaired a problem with a sensor, it then ran into trouble with the car's battery that limited its action.
Massa posted the third-fastest lap in his Williams. He had announced he was retiring, but returned to Williams when Bottas left last month.
F1's rule changes to produce more downforce and grip by mandating wider vehicles and tires appears to have led to the desired result of boosting speeds.
To compare with times on the same track from last year, Hamilton's fastest effort of 1 minute, 21.765 seconds on Monday knocked a second off the fastest lap through a full eight days of testing in 2016. It was also faster than Hamilton's pole-winning lap of 1:22.000 at the Spanish GP.
Some drivers said the new designs allowed faster speeds on curves, which meant more was being demanded of them physically.
''I definitely put my body to the test today,'' Hamilton said.
Alonso, despite his disappointing start, said F1 ''is going in the right direction again.''
''You can express your driving style,'' he said. ''Last year the slower you drove, the better lap time you could do in order to save your tires.''
The opening test will run through Thursday.
The track near Barcelona will host a second round of testing from March 7-10 before the season starts at the Australian Grand Prix on March 26.