The Mercedes driver completed a whopping 156 laps at the Circuit de Catalunya -- where the Spanish Grand Prix lasts for 66 -- to eclipse the mileage of all his rivals as the new cars hit the track for the first time.
Ferrari's Sebastian Vettel, who was fastest overall and 0.470 of a second quicker than the 31-year-old Briton, did 69 laps in total.
"Today is just a real show of just how amazing this team is," said Hamilton. "From as far as I can remember, and I've been driving a long time, I'm certain this is the most impressive first day I've had," he added.
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"If you look back at the first days I've had in 2013 and maybe 2014, I had those glitches with the brakes so it's nice to have a clean day without any issues with the car. Really just go above and beyond."
Hamilton, champion in 2014 and 2015 with Mercedes, had completed a race distance by lunchtime and told reporters anxious for first impressions that the car felt just like last year's dominant one.
Mercedes won 16 of 19 races last year, taking both the driver and constructor titles, and have triumphed in 32 of the last 38 grands prix.
Valtteri Bottas was third quickest in a Mercedes-powered Williams in the morning but Red Bull's Daniel Ricciardo ended the day in that position with the Finn fourth.
McLaren's Jenson Button revived optimism at his Honda-powered team with 84 largely trouble-free laps in a refreshing change from a dismal 2015 when the former champions finished ninth out of 10.
There was also a hint of change at the slower end with backmarkers Manor, now using Mercedes engines, quicker than Renault and newcomers Haas and German rookie Pascal Wehrlein also doing more laps.
Renault's British rookie Jolyon Palmer, whose former Lotus team were taken over by the carmaker in December, was last on the timesheets.
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 20 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 said.
(Editing by Ken Ferris and Ed Osmond)
