Sainz believes engine is reason for form dip

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.

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.