Triple Formula One world champion Lewis Hamilton completed a race distance before lunchtime on the first day of pre-season testing in Barcelona and, ominously for rivals, said his new Mercedes felt like a winner.
"First impression? It feels good, it feels like last year's," the Briton told a scrum of reporters at Barcelona's Circuit de Catalunya when the morning session ended.
Mercedes won 16 of 19 races last year, taking both titles, and have triumphed in 32 of the last 38 grands prix.
"It's very encouraging," added Hamilton after doing more mileage than anyone else. "It's a great job by the team. Usually in the first day you don't get that many laps so I'm really happy."
Hamilton managed 66 laps -- exactly the same number as the Spanish Grand Prix held at the same circuit -- without any obvious problems.
The 31-year-old Briton was not the fastest -- Ferrari's Sebastian Vettel led the timesheets -- but lap times matter less than reliability as teams look initially for consistency over outright pace.
Quadruple champion Vettel, in his second season at Ferrari, did 36 laps.
Hamilton was 0.470 seconds slower than Vettel with Finland's Valtteri Bottas third quickest in a Mercedes-powered Williams and completing 43 laps.
Despite the strong showing, Hamilton -- who has won the past two championships and is aiming to become the first Briton to win four world titles -- said the season starting in Australia on March 20th would be tough.
"Every year you have to expect it to be harder. In terms of my preparation, I'm preparing for the hardest season I've had so far," he declared.
Monday was the first day the new cars had been seen in public with only Sauber yet to show theirs. The Swiss team are testing with a 2015 car and will not have the new one ready until the second four-day test next week.
The U.S.-based Haas F1 team made their debut, and triggered the first red flag of the season when Romain Grosjean's car shed its front wing and marshals were called in to sweep up the debris. Renault returned with their own team.
Red Bull-owned Toro Rosso, who have yet to finalise their look, took to the track with a plain blue car lacking any branding.