Toro Rosso keeps Pierre Gasly, Brendon Hartley for 2018 F1 season

The team has ended the year with Hartley and Gasly as its drivers after starting the season with Carlos Sainz Jr and Daniil Kvyat - with the Spaniard switching to Renault early and the Russian being dropped.

While Gasly was the latest driver to emerge from Red Bull's junior programme, World Endurance champion Hartley has enjoyed a reunion with the energy drinks firm's F1 programme after being dropped from its ladder system in 2010.

"We're really happy to have Pierre and Brendon confirmed so early by Red Bull as our drivers for 2018," said team principal Franz Tost.

"During this last part of the year they've shown that they're ready for Formula 1, getting to grips with the car quickly, showing good performances and always demonstrating to be prepared for the challenge.

"As we know, F1 is something that not all drivers can adapt to this fast.

"Therefore, we're looking forward to having a full year with them; one where we can hopefully provide them with a good package which, combined with driver consistency, can surely put them in the best possible situation to deliver."

Gasly has made four starts for Toro Rosso this season, missing the United States Grand Prix to contest the Super Formula finale that was abandoned, which created the opportunity for Hartley to make his F1 debut in his place.

"I'm super happy to race for Toro Rosso in 2018, for my first proper season in Formula 1," said 2016 GP2 champion Gasly.

"I would like to thank all the people involved, who helped me get here: Red Bull, Toro Rosso, my family and all the ones who have supported me in the lower series.

"I'm really excited and super motivated to give it my all in Abu Dhabi and the whole of next year. I just can't wait."

Hartley, who appeared on course to switch to IndyCar following Porsche's withdrawal from the LMP1 category of the WEC, added: "It's very satisfying to have converted an opportunity that came as a surprise into a 2018 F1 drive, I couldn't be happier.

"I'd like to thank Red Bull and Toro Rosso for believing in me and giving me this second chance - dreams can come true.

"I'm now going to carry on working harder than ever in order to finish this busy end of season on a high and start the new year as strong as possible. Bring it!"

Neither driver has scored points yet for Toro Rosso, with Gasly's 12th place in Brazil last weekend the best finish achieved so far.

2018 F1 driver line-up so far

Mercedes: Lewis Hamilton, Valtteri Bottas
Ferrari: Sebastian Vettel, Kimi Raikkonen
Red Bull-Renault: Daniel Ricciardo, Max Verstappen
Force India-Mercedes: Sergio Perez, Esteban Ocon
Williams-Mercedes: Lance Stroll, tba
Toro Rosso-Honda: Pierre Gasly, Brendon Hartley
Renault: Nico Hulkenberg, Carlos Sainz Jr
Haas-Ferrari: Romain Grosjean, Kevin Magnussen
McLaren-Renault: Fernando Alonso, Stoffel Vandoorne
Sauber-Ferrari: tba, tba