World Endurance Champion Sebastien Buemi will remain the Red Bull Formula 1 team's reserve driver in 2015.
Buemi, 26, started 55 grands prix for Toro Rosso between 2009 until 2011 before resuming reserve driver duties for Red Bull when he and STR team-mate Jaime Alguersuari lost their
F1 race drives to Daniel Ricciardo and Jean-Eric Vergne.
Red Bull boss Christian Horner said Buemi had since become an invaluable part of his F1 squad's set-up.
The Swiss dovetailed his 2014 F1 reserve duties with a victorious WEC campaign for Toyota alongside British racer Anthony Davidson, and is also currently contesting the inaugural Formula E championship, in which he lies second for the e.dams squad after the first three races.
Buemi said he was looking forward to helping Red Bull attempt to recover from losing its world champion status to Mercedes this year.
"It is like being part of the family and I have a good working and personal relationship with everyone at the team," he said.
"I'm looking forward to helping with the development of the RB11 in any way I can.
"It should be an exciting season and I'm delighted that I will be a part of it."
