Although Renault are not where they wanted to be after the second test, Rob White is confident they have taken "several" steps forward.
After the disaster that was Jerez, Renault had hoped for a solid second test at the Sakhir circuit in Bahrain.
And although it was an improvement, Renault-powered teams managed just half the number of laps completed by the Mercedes runners.
They were also off the pace with Pastor Maldonado's 1:38.707 the fastest time set using Renault power, a massive five seconds down on Nico Rosberg's best in the W05.
"We have had some set-backs, but we have definitely made progress and have taken several steps forward," said White, Renault's deputy managing director.
"The changes have improved the PU behaviour in the car and we are have accumulated valuable mileage. There have been stoppages, on our side and on the chassis side as well, but we have ironed out some important faults and allowed the teams to gain crucial experience of the car as a whole.
"We have seen that minor incidents can cause downtime that is difficult or impossible to recover. In particular, we lost more time than anticipated on the final day.
"While we are not at the level of operation and performance we would want to be, we have a more solid basis to work from, and we are moving in the right direction."
Pressed as to how far behind schedule Renault are, White said where they stand at the conclusion of the second test is where they had hoped to be halfway through the first.
"We have made some good headway, in terms of PU performance and operation in the car, we are now in a situation we could have accepted mid-Jerez. We have solved some problems and revealed some others," he explained.
"We are not back on schedule but we are moving in the right direction - the running we have done is very valuable. The challenge is to improve the rate of progress, because the gap to where we wanted to be at this stage remains substantial.
"We are some weeks behind where we wanted to be, and we acknowledge it will take time to unlock the full performance of the PU. We are working hard to get there and we are determined to succeed. We remain confident in the PU and its sub systems, we are just not at the level of operation and performance we want to be.
"The immaturity of the PU combined with the time lost to incidents, means the chassis work to prepare for the season is also behind schedule. From this point on we must pursue and accelerate an upward curve."