Hartley had Toro Rosso F1 2018 deal confirmed 'weeks ago'

Brendon Hartley may only have been formally announced as a Toro Rosso Formula 1 driver for the 2018 season on Thursday, but the New Zealander has revealed the deal was signed and sealed "a couple of weeks ago".

Porsche factory driver Hartley made his shock F1 debut with Toro Rosso at the United States Grand Prix, seven years after being ditched by Red Bull's junior programme, and retained his seat for the remainder of the 2017 season.

Toro Rosso team boss Franz Tost hinted over the Mexican Grand Prix weekend a continuation with Hartley and Pierre Gasly was likely for 2018, with the line-up being made official by the team on Thursday.

When asked by Crash.net when he got confirmation he had been retained, Hartley said: "That’s a good question… a couple of weeks ago. A little bit before the media.

"It wasn’t a surprise when I read it yesterday, let's say that.

"I'm really, really happy. Right now the focus is on this [FIA World Endurance Championship race] weekend, I’ve been saying that for a while from race to race.

"But I couldn’t be happier and it’s a massive opportunity for me. I'm delighted, I don’t know what else to say to be honest."

Given he will embark on his first full season in F1 with just four races of experience under his belt, Hartley is under no illusions about the challenge he faces, but said he already feels at home at Toro Rosso.

"I have a big challenge ahead and I’m happy with the progress that I made in the few weekends that I’ve had," Hartley said.

"I’m quite aware that there’s still work to do and Formula 1 is a tough business, constantly changing and constantly needing to adapt.

"So far I feel pretty comfortable and the team have been great, I feel right at home inside the paddock.

"It’s exciting times for me. But I’m quite aware that there’s some hard work ahead."