McLaren is still years from closing the gap to Formula One champions Mercedes and runners-up Red Bull despite enjoying its best season since 2012, according to team principal Andreas Seidl.
The former champions reclaimed third place overall at the Abu Dhabi season-ender on Sunday.
"We need to stay realistic. Despite the good result we have this weekend and, despite the great outcome for us in the championship side with P3, I think we know exactly where we are," Seidl told reporters.
"There's still a huge gap to the cars in front, especially the Mercedes."
Mercedes won both titles for an unprecedented seventh year in a row and scored 573 points with seven-times world champion Lewis Hamilton providing 347. McLaren scored 202.
McLaren has not won a race since 2012, Hamilton's last season with them, but have climbed back from ninth in the constructors' standings with former engine partner Honda in 2017.
"The team this year, under the leadership of (technical director) James Key, has produced a very competitive car, a great step forward compared to last year," said Seidl, who joined last year.
"Still, we know what the gap to the Mercedes is. It is not something we will close from one year to the next year. We still know that we have a lot of deficits within the team in terms of organisation, in terms of infrastructure, which we need to close first.
"It will take time. But I'm confident that if we do the right things on the team side, we can close these gaps in some years."
McLaren is planning a new wind tunnel at its Woking headquarters but it will be some time before that comes on stream.
Seidl expected next year, with the cars largely the same before major change in 2022, to be another battle between four or five teams for best of the rest behind the top two.
McLaren have Australian Daniel Ricciardo, a race winner with Red Bull, joining from Renault to partner Britain's Lando Norris after Spaniard Carlos Sainz leaves for Ferrari.