Charles Leclerc admits he didn't expect Sauber's C37 to perform as well as it did in the latter part of the season given the team's total lack of development work.
Sauber's performance in the first few races of the 2018 season were nothing to write home about, but progressively the Swiss outfit improved and found its spot among the mid-field runners.
However, with the team's resources being directed early on over the summer towards next year's car, stagnant performance from the Hinwil squad was expected in the last few races.
But Leclerc enjoyed top-ten finishes in Mexico and Brazil while team mate Marcus Ericsson qualified an impressive P7 and 'best of the rest' at Interlagos.
"The baseline of the car this year is good, I just think in the first three races we didn't use the full potential," said Leclerc.
"Once we understood how to balance this car we really did a huge step up. Then we made some improvements during the season also that made it even better.
"The car is very impressive compared to last year, you can see that in the results."
"We have stopped the updates on the car since quite a bit [of time ago] and we are still keeping the same performance, as are the teams that are trying to push a little bit.
"So it's definitely a strong car."
Leclerc wasn't expecting Sauber to sustain its level of performance after switching its focus to next year's car, but the 21-year-old believes the early start bodes well for 2019.
"I don't think we expected to have such a good end of the season [after] expecting the end of development process for this year's car so early on," said the Ferrari-bound driver.
"It's definitely looking good for them for next year because they've had quite a bit of time to develop the car."
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