Carlos Sainz is certain that Renault has made a "big step" with its power unit for 2019, having delivered the fastest lap time of pre-season testing thus far on Wednesday. Sainz's time of one minute 17.144 seconds came in an impressive 130-lap programme in the McLaren.
Sainz's headline time is not only the quickest of this year so far, but also faster than the top time of 2018, set by Ferrari's Sebastian Vettel – flying in the face of suggestions that 2019's cars would be slower than their immediate predecessors.
Although Sainz remains wary of reading too much into Renault's improvements, the former works team driver says the progression is notable from the cockpit.
"It feels like a good step, that's the only thing I can say," Sainz said, when quizzed on Renault's improvement by GPFans.
"Until anyone turns up the engines in Australia, and we see the top speeds, it's going to be very difficult to find out how good the step is, or if the others have made a step as big as we have done.
"My initial guess is: I feel it, I feel a big step on the engine and it's going in the right direction."
McLaren's form deteriorated badly last year, indeed Fernando Alonso's fifth-place finish at the season-opening Australian GP was their best result across the campaign.
However, Sainz sees an upward trend in their development through 2019 so far.
"The car has been progressing, the car balance has got better and it's allowing us to extract more from it, so it means things are working well," Sainz explained.
"We're understanding the underlying issues and correcting them little by little, but we're still not where we want to be and we need to work hard.
"[A lap of] 17.1 in Barcelona is fast, but the Ferrari, Mercedes and Red Bull can go much faster so I'm cautious for now."