Porte, who lost 51 seconds in the opening stage after being delayed behind a pile-up, helped his team edge out Team Sky by four seconds after they completed the 35.5 kilometre circuit around Cholet in 38 minutes 46 seconds.
BMC clocked 38min 46sec as their Belgian rider Greg van Avermaet took the overall leader's yellow jersey, with Sky in second place, four seconds behind. "To win the stage with a team like we have here, and especially with the passing of Andy Rihs, is special", Porte said. "We're on track but there's still so much to go through".
"We'll try our best for the team, it'll be hard but you never know in cycling", said the yellow jersey wearer on his chances of holding on to it. "It wasn't ideal to throw 51 seconds away but we have taken some good time back on some of the other GC (general classification) guys today".
The three-time defending world champion took the overall lead of the Tour on Sunday after he bettered about a dozen other sprinters to win Stage 2. "I love France and the Tour, which is the most attractive race on the planet". "I am a lot happier than I was at the Dauphiné, we have a gelled unit here and a powerful one". "That's the nature of the game".
BMC were among the pre-stage favourites and demonstrated why, celebrating another victory three years after they won the last team time trial stage on the Tour.
"You have to focus, we are aiming at getting flawless execution", he said.
Among the big losers today were Nairo Quintana, whose Movistar team came home 53 seconds down on BMC Racing, Bahrain-Merida with 2014 Tour de France victor Vincenzo Nibali, 1 minute and 6 seconds down, and Romain Bardet's AG2R-La Mondiale, who came home 1 minute 15 seconds behind the day's victor.
Sky finished second and Quick-Step Floors came third, seven seconds behind.
"To be honest I didn't even think about it (the yellow jersey), it was just about winning the stage".
There was a festive family atmosphere on the mainly coastal route, which was well marshaled by a massive police presence that organizers hope will deter fans targeting Froome, who was only cleared to race last week after long-running suspicions of doping were put to bed.
"Obviously it was a tough one today but the big strong guys did a great job and it was a flawless team time trial", Porte told Cycling.com. "It just shows that we are here, too, and let's get it on".
Kiwi rider Patrick Bevin leads BMC Racing through the team time trial course on the Tour de France. "Close but not quite quick enough".
While Sky missed out, victory was a boon to Porte - a year to the day after he was hospitalised by the serious crash which ended his 2017 Tour - and the BMC team whose future remains uncertain as they seek a new title sponsor.
"We're happy, we had the yellow and that's part of history".
"A team time trial is always a something special when the whole team makes efforts for the same goal", Van Avermaet said.