A successful day from the point of view of seat time, Carlos Sainz says there is more to be desired from the Renault power unit.
The biggest concern for Toro Rosso is extracting the most amount of power from the Renault power unit ahead of this weekend's season-opening Australian Grand Prix.
That is according to rookie driver Carlos Sainz, after two free practices that saw the Spanish driver end up seventh of the 16 cars during the second of the Friday sessions.
"At the moment, to be honest, it is our main concern," he said.
"We are working on it, we are bringing it forward to our Renault guys.
"There are still some steps to be done before tomorrow, steps where we have not extracted all of the performance from it and there is still a margin for improvement.
Seat time for the rookie
Aside from getting more out of the power unit Sainz said he is happy with his first day behind the wheel of the Toro Rosso STR10.
"A lot of mileage covered today. I have to tank the team for that, because as a rookie that is what you want," said Sainz.
Sainz added that he thinks the running order will change, considering some teams still may not be showing their full potential.
"I think we are in a decent position performance wise right now, I feel comfortable with the car, especially on one-lap performance. We have no ideas where the others are, we know I am comfortable, but we have no idea how hard the others are pushing."