Renault has admitted that its upgraded power unit did not deliver the anticipated step forward in performance at the Brazilian Grand Prix.
Red Bull installed the updated unit into Daniel Ricciardo's RB11 but the Australian expressed disappointment after qualifying, believing that using the modified engine was not worth the 10-place grid penalty which came with it.
Renault chief Remi Taffin was encouraged by the power unit's reliability, but concurred with Ricciardo's comments.
"From a technical standpoint, we tried out the new ICE [Internal Combustion Engine] upgrades in Daniel’s car," he said.
"The engine ran reliably, but unfortunately it did not deliver the expected improvements in performance.
"All the same, the reliable running ensured we gathered a lot of data to analyse how we can move forward to the final race of the year and going into the winter.
"Daniil [Kvyat] and Max [Verstappen] had solid races and were able to fight for positions, but it’s not been the most memorable race to be honest."