The Monegasque rookie finished the Brazilian Grand Prix in P7, ‘best of the rest’ behind the top three teams.
Sauber have consistently made the biggest gains compared to last year, when they were bottom of the Constructors’ standings.
“I don’t think we expected to have such a good end of the season, [with] the end of the development programme for this year’s car so early,” Leclerc said.
“So it’s definitely looking good for them for next year, because they’ve had quite a bit of time to develop the car.”
For the final race of this season, though, Sauber will be looking to stay ahead of Toro Rosso in the standings, a position they took in Brazil.
“We’re obviously not going to take stupid risks to gain one position if they are behind,” the Monegasque driver added.
“That’s for sure going to change a little bit our approach.
“But the goal remains the same, to do the best job possible every week, and to obviously keep them behind.
“We will change a little bit in some situations.”