Hartley in the dark over F1 future after Toro Rosso US GP debut

Porsche World Endurance Championship driver Hartley, who used to be part of the Red Bull junior scheme, replaced Super Formula title contender Pierre Gasly for the Austin race and finished 13th in his first single-seater race since 2012.

Gasly is thought likely to return to Toro Rosso for this weekend's Mexican GP, after the Super Formula finale was rained off, and there were suggestions in the Austin paddock that Hartley could be retained as Gasly's team-mate instead of Daniil Kvyat, who finished 10th as a replacement for new Renault signing Carlos Sainz Jr in the US.

But Hartley says he is yet to receive an indication from Red Bull or Toro Rosso that he might be retained for the next race or beyond.

"Up until this moment I haven't been asking the question," Hartley said. "And it was the same when they called me up to do a simulator test.

"I didn't want to know, I just did the job, and that's how I've taken this weekend.

"I've actually been really relaxed and I'm happy I did it that way.

"I guess now there might be some conversations. I really don't know. You'll have to ask them."

Rookie errors

Hartley admitted he did not make the best start to the race, and could have made better decisions when fighting for position with Lance Stroll's Williams.

"I nailed some of the practices, but when it came to the real one, it's been a while since I've done one," Hartley added.

"My start wasn't very good - I didn't nail that.

"I'm pretty happy with the first lap - there was a bit of a tussle with Stoffel [Vandoorne].

"It was the first time I've put 20 laps on these Pirelli tyres - it was going into the darkness in terms of what was going to happen. Managing tyres, I think I was probably too conservative.

"At the end of the last stint I started to understand a bit more, and was pretty happy with the performance.

"I was a bit disappointed that Stroll passed me after the pitstop and I got stuck behind him.

"That's another lesson learned - I should have got on the overtake button, but I thought he was far enough behind.

"There's always things you can do better. If I was to do the race again, with the experience I've gained, I would do some of it a bit differently.

"So many experiences I can take going forward, if I get an opportunity."