Daniil Kvyat has suggested that there are further improvements to come from Red Bull's Renault engines before the start of the Formula 1 season.
Red Bull struggled to match the pace of constructors' champions Mercedes on Friday's test day in Catalunya, but Kvyat believes that the team's power units are still not maximising their potential yet.
He is quoted by ESPN as saying: "In the end these are the tests and we are always trying to improve any area.
"We are working on our chassis, on my side I am always trying to make my best to make the car go faster on corners. This is why I am a driver, I cannot do anything down the straights - this is the business of someone else. We obviously expect more steps from Renault's side and hopefully we will get them.
"There is always some room for improvement. Of course we are looking for a further step forward because we always want to be faster. The competition level seems to be very high, the benchmark seems to very high but we are keeping our head up and put all the positives together and take the best from our package."
Red Bull finished second in the 2014 constructors' championship, with driver Daniel Ricciardo registering three race wins during the campaign.
