Fernando Alonso says his Formula One future will depend on the direction the sport takes over the coming years and whether it can put the focus back on drivers.
Alonso won two drivers' championships in 2005 and 2006, but a series of poor career decisions and missed opportunities have seen him finish runner-up three times since then without securing another title.
Since the introduction of F1's turbo hybrid engines in 2014, Alonso has not won a race or finished higher than sixth in the championship, and he last fought for a title in 2012 -- when he missed out by three points while driving for Ferrari.
In 2010 he was four points away from a title victory, while also driving for Ferrari, but he claims he has not had a car worthy of a championship since 2007 -- when he went up against Lewis Hamilton at McLaren and both drivers missed out on the title by a single point to Ferrari's Kimi Raikkonen.
"I think it has been up and down," Alonso said when asked how much longer he could continue without fighting for victories. "I think the last possibility of the last championship car we had was 2007. The rest has been always quite far off from the performance of the top and the winning team of that season.
"We're now 11 years after that moment, so I don't think it's a problem [for me to be off the pace] but I think the biggest thing for me is to think about the direction Formula One is going and I don't think too much about how competitive we'll be next year as it is impossible to predict. It is just about the sport.
"When you see again the grid in Canada there were two Mercedes, two Ferraris, two Red Bulls, two Force Indias and two Renaults in Q3. It is a constructors' world championship and not a drivers' world championship so it is something I need to decide."
Asked if he felt he had not won as many championships as he deserves, Alonso said the situation is worse for other drivers.
"No not really I think there are opportunities missed in the past, and we could have won probably four or five championships by I think seven points one time, and then three or something like that. But at the same time I feel extremely privileged to have this 18 years in F1 and I know there are drivers here that I race against, I see them on the track, I see their talent, I see their previous categories, and they've never even reached a podium.
"I see my teammate now [Stoffel Vandoorne], I see Nico [Hulkenberg], I see Carlos [Sainz]. I see a lot of talented drivers that they didn't score a podium. At the same time, we missed some opportunities as I said but I'm happy with the things that I've done."
Alonso is racing at the Le Mans 24 Hours this weekend in pursuit of motorsport's Triple Crown -- victories at the Monaco Grand Prix, Le Mans and Indy 500 -- and will race for favourites Toyota.