The 31-year-old joined German team mate Nico Rosberg at a wintry Silverstone circuit for a filmed promotional day ahead of official pre-season testing that starts in Barcelona on Monday.
Between them, they covered 98.2km in the session run behind closed doors. Under Formula One rules, teams are allowed to do a maximum of 100km outside official testing on designated filming days.
Rosberg, whose disappointment at finishing overall runner-up for the second year in a row was tempered by ending the season with three successive race wins, had first go in the F1 W07 hybrid and sounded positive.
"It was a good feeling to start with. I felt at home straight away. I could push as if I raced Abu Dhabi yesterday so a good beginning," he told Sky Sports television, referring to last season's final grand prix.
Mercedes won all but three races in 2015 and have been triumphant in 32 of the last 38.
"Everything has gone very well," said technical head Paddy Lowe. "We haven't even taken the engine cover off yet in the whole morning session which is a really good sign of the reliability that we've achieved at this point."
He said the latest specification engine, even without running at full throttle, was "a little bit louder" than last year's.
Ferrari, who presented their new car online on Friday, closed the gap last year and Lowe said the Italian team would again be pushing them hard.
"We see them as our main threat coming out of where all the teams were last year," he said. "It remains to be seen how we position ourselves in the weeks to come.
"Ferrari definitely are a very strong competitor and one we worry about. It keeps us motivated to keep pushing all the time."
Hamilton will be in the new car on the first and third days of testing at the Circuit de Catalunya, with Rosberg driving on Tuesday and Thursday. The running order is the reverse of last year's opening test.
(Editing by Tony Jimenez)
