Sainz surprised himself since Renault switch
Carlos Sainz Jr has admitted he did not expect "to be so competitive" with Renault after switching Formula 1 teams in the final third of the season.
The Spaniard replaced Jolyon Palmer from the United States Grand Prix and immediately outqualified Nico Hulkenberg, who had not been beaten by Palmer in qualifying all year, then finished seventh in the race.
That performance drew glowing praise from Renault, and Sainz started eighth in Mexico but spun early in the race before eventually retiring with a steering problem.
When asked if he had surprised himself by how well his switch from Toro Rosso had gone, Sainz said: "A bit yes. I knew from the past when I switched teams in the lower categories, or when I did a test in F1 in 2013, that I could adapt very quickly to whatever you give me.
"I know I am good at that, but I didn't expect to be so competitive right from the start.
"It has been a positive start in that sense.
"I still have a long way to go, I think Nico is still a couple of steps ahead, but I am catching up and hopefully I can catch up before the end of the season."
Reliability remains a big cause for concern at Renault but Sainz says the early impressions of how the team operates, and the scale of progress at its Enstone factory, have left him bullish about the potential for next year.
"I think the main progress has to come from the power unit and reliability - and that will immediately help our chances of being higher in the standings," explained Sainz.
"As well as that, with all the infrastructure and all the resources back in Enstone, I can only see the team going forward from now.
"They all look positive and motivated and it is good to see - it is good to arrive at a team where everyone is so happy and motivated."
Sainz thinks that getting four races under his belt at the end of this season will be a significant boost in understanding the car and how the team operates.
"I now have a feeling for this car too, and what I can do for next year to try to suit it a bit more to my liking," he said.
"This car has been developed for 16 races around a certain driver, even the cockpit, the comfort of the seat, everything - it has been developed around someone else.
"So to have these four races, to have the opportunity to give feedback in what I would like for next year, is super important and could give us a good baseline for 2018.
"It means I will not be arriving at the winter tests and having to say these things then.
"I'm doing them now and having a good headstart."