Toro Rosso team principal Frans Tost believes rookie Daniil Kvyat "is doing a fantastic job" while he feels there "more to come" from Jean-Eric Vergne.
The Faenza-based squad have had a mixed year so far with Kvyat and Vergne regularly making it through to Q3, but they have often failed to back that up on race day as they have scored just 15 points between them.
Although rookie Kvyat has scored only six points, the youngster has impressed a lot of people in his debut campaign.
"He is doing a very good job, taking into consideration how little mileage he was able to do before the season, he is driving very well, showing that he has natural speed," Tost told the official Formula 1 website.
"Equally importantly, he has had no accidents, nor has he made any mistakes. He is doing a fantastic job.
Vergne, in his third season with the team, has also looked solid in patches, but he has been troubled by reliability issues.
"He has suffered a lot with reliability issues, but when his car was running fine, he delivered good performances," Tost said. "Thanks to his experience he makes an important contribution to the team's technical development and I'm convinced that there is still more to come from him."
Kvyat and Vergne have suffered nine retirements between them this season and Tost admits it is something they need to sort out if the team want to move ahead.
"It has to improve, even if we are on the right road," he said. "But as I said before, on the reliability front, we have too many deficiencies. We are working hard on this area and I hope we will already see the results of our efforts during the course of this year."