Fernando Alonso says 2019 decision is 'goodbye' to F1

Alonso is expected to combine an IndyCar programme with his Toyota WEC commitments in 2019, having announced over the summer break that he would not continue in F1 with McLaren.

"Right now, I am thinking that it's a goodbye," he said. "But life changes very quickly.

"And life also taught me in the past how things may change, in a couple of months' time, or years' time.

"As I said also in the press release when we announced the retirement it is to leave the door open, because I don't have a crystal ball to know what is going to happen in the future.

"For me it is a bye-bye, but who knows what will happen?"

Alonso insisted that he wanted to leave F1 on his own terms, having wanted to see how McLaren's changes for 2018 played out before committing to anything.

"It was a decision that probably I started thinking about last year, and then this year, there were a lot of changes into the team, with the engine manufacturer changes and things like that, so I thought that it was worth staying one more year," he said.

"I enjoy driving these cars with these regulations, the big tyres. I was having fun.

"But at the same time I make some changes and some priorities into this year with the WEC championship and other things also towards this direction.

"A couple of months ago I decided that it was the right time, I feel strong, driving a good level and I want to say bye-bye to this sport when I feel strong, not when I feel not competitive, or I don't have any place to go or whatever.

"I prefer to take my own decision and find new challenge that maybe F1 cannot offer me at the moment."

The Spaniard insists that winning in other categories is the best way for him to leave a legacy after he has been unable to extend his tally of two F1 world championships.

"I think the challenges [away from F1] are probably bigger than the challenges that I can find here for next year," he said.

"To be best driver in the world, there are two possibilities, winning eight world championships in F1, which is unlikely now for me, or second is to master different series and different cars.

"In sportscars I'm doing OK at the moment, so I'm happy with the performance I'm seeing there.

"The Indy 500 I felt competitive last year, and there are other series that can put you in a different level in motor sport, if you can win.

"There are probably only two teams [in F1] which can win and they continue with their drivers for the following years.

"If you are in one of those two teams you probably keep going even if you don't enjoy the races or trips or amount of years you have been doing the same thing."