Team principal Martin Whitmarsh said 2014 has already started for McLaren, and it was important to finish "a long, hard and disappointing" season with the team's "best grand prix of the year."
Jenson Button finished fourth at Interlagos for McLaren's best result of 2013, and teammate Sergio Perez had a remarkable sixth-place finish after starting 19th. They hadn't finished higher than fifth heading into Sao Paulo.
"This is a great way to end the year, and now our focus turns squarely to 2014," said Button, who started 14th at the Brazilian GP. "McLaren is an incredibly strong and powerful organization and, believe me, we will fight back."
The finish in Brazil also meant McLaren became the first team in F1 history to have both cars classified in every race of the season. In addition, Button became the first British driver to race in 247 grands prix, surpassing the record of David Coulthard.
"Undoubtedly, that was our best grand prix of the year," Whitmarsh said. "It's frustrating to have to say that after a race in which our drivers finished only fourth and sixth, but it's also true."
It was the first time in decades that McLaren drivers failed to reach the podium in a season. Button ended ninth in the drivers' standings and Perez was only 11th.
"2013 has been a long, hard and disappointing year," Whitmarsh said, adding that the team is already working on incorporating the new rule changes for next season.
"Formula One is a relentlessly demanding sport, and next season's new regulations are already presenting all the teams with a daunting array of technical challenges," he said. "For quite some time we've been working extremely hard on those technical challenges, and our focus will be unstinting and unwavering from now onwards, throughout the winter.
"In other words, the 2014 season starts this evening," Whitmarsh said after Sunday's race.
Teams will have to switch from 2.4-litre V8 engines to a 1.6-litre V6 turbocharged unit near year, a move that will demand significant changes in the design of cars.
McLaren will also have a new driver next year as Perez will be replaced by rookie Kevin Magnussen of Denmark.
"I've learned so much from everyone at McLaren," said Perez, who is still without a ride for next year. "The best team I've ever raced with, and I wish every single one of them all the best for the future. I wish Jenson and Kevin all the best for the future."
Next season McLaren won't have sponsor Vodafone, which was a partner for seven years.
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