Renault driver Carlos Sainz Jr. believes there has been a lack of progress on his side's engine during the second half of the season and this has contributed to their recent dip in performance levels.
Sainz believes that because Renault haven't introduced an engine upgrade in the second half of the season, it has ultimately damaged their performances.
Renault opted not to take the C-Spec version of its power unit due to concerns over its reliability, despite Red Bull showing off its performance.
"There was probably a big setback with the engine side," Sainz said to Autosport. "We didn't expect Ferrari and Mercedes to do such a big step through the year. We though that the B-Spec was probably going to be just enough, but we've seen at the moment that it is not enough.
"We brought things to the chassis - probably the chassis is not that bad - but on the top speed side we are not where we want to be."
Sainz was asked his opinion on whether his team should have taken the C-Spec engine as its third power unit in hindsight and the Spaniard replied: "If it comes without reliability, no.
"The team is fully sure that with our fuel it is just not reliable enough, so I fully back the team with whatever decision they take. I think we need more power, which we don't have, and we don't get it for whatever reason.
"If we wanted to be in Q3 in Japan, we just needed more power, and Honda has showed that it is possible."
Read more about:
Today
Popular on GPBlog
1
Stella thankful it was Hamilton Piastri made daring move on: 'Very fair competitor'
772 times read
2
'Red Bull are the much more fun team; Mercedes are more professional'
627 times read
3
'Russell and Antonelli are a safer bet to Verstappen, and a lot cheaper too'
609 times read
4
F1's high profile bromance in peril? 'We are fighting for our careers in F1'
561 times read