Wehrlein scored all five of Sauber's 2017 points via eighth place in the Spanish Grand Prix and 10th in Azerbaijan, but has lost his seat to Formula 2 champion Charles Leclerc for '18 amid Sauber's enhanced relationship with Ferrari and new Alfa Romeo tie-up.

Though the Barcelona drive was the statistical high point, Wehrlein reckons he performed better than that in the second half of the season - when Sauber's declining form meant the best he could do was 12th in Singapore, and he ended the year with three straight 14th places.

"In terms of result, [Barcelona] was the best race of the year but probably in the second half of the season I had better races, but you couldn't see it," said Wehrlein.

"Even if we had a good race in the second half of the season, you couldn't see it because the gap was just too big - for example, in Suzuka, I was lapped by the second-last guys.

"I'm quite happy in the end with five points. Not all of the races have been good as I wished but I think in general we did what we could do."

As well as Sauber falling away from its rivals, Wehrlein said his own form was hampered by extra issues for much of the latter part of the year.

He said engine problems afflicted him "from Austria to Monza" and "in Japan and Austin the car was all over the place".

Wehrlein was among the long-shot contenders for the Williams seat now likely to go to Sergey Sirotkin. He has now been tipped for a return to the DTM with Mercedes next season.

The 23-year-old added that he was sure he could still return to F1 after 2018 if he had to race elsewhere for a season, joking "I won't retire!" when asked if he feared missing next year would end his F1 career.

Wehrlein said he could look back on 2017 with no regrets and underlined that he was still developing as an F1 driver.

"Definitely I was always giving my best, and I think that's the most important thing that you can say about yourself," he added. "When an opportunity was there, we took it.

"With more experience you think 'ah, one or two races ago I was doing this direction with the set-up, now I know this was worse I should have gone in this direction', and you always learn something."