Toro Rosso’s technical chief James Key has been left impressed by the progress made by engine supplier Renault over the course of the winter.
After using year-old Ferrari engines in 2016, Toro Rosso has returned to Renault power for this season.
The French manufacturer has completely revamped its power unit in a bid to close the gap to pacesetters Mercedes, having lagged behind its German rival in first three years of the hybrid era.
Key believes Renault’s efforts at its base in Viry Chatillon are paying off, with the figures achieved in dyno translating into on-track performance.
"I think the good thing with Renault is on the performance side, since we've been with them, they've turned a huge corner," he said.
"Our impressions are positive -- exactly where it stands in the order is impossible to say at this stage, but there's definitely a vast improvement from what we saw in the past.
“You can see that, that's real, it's not just a value coming out of a dyno, I think it's real. So from a performance point of view we're happy with what we're seeing so far."
"We know winter testing is very difficult to tell of course, so it's always with a caveat but it does appear to be very tight. If you do the calculations, much depends on fuel levels and where people are running their engine and that sort of thing -- we're pretty conservative right now anyway despite the tyres we're using -- but I think it looks tight.
With teams yet to focus on performance runs in testing, Key believes it is too early to make predictions about the pecking order. However, he expects a tight midfield battle involving Haas, Renault, Williams, McLaren, Force India and Key’s own outfit, Toro Rosso.
"I think Haas look quite reasonable, I have to say. They look in reasonable shape just looking at the numbers, we'll have to see how that develops next week and into Melbourne but they appear to have done a good job. Renault could be tight with them, we'll have to see but they look on balance more competitive than they were last year.
"Williams is difficult to tell at the moment I think, and I think it's difficult to tell with Force India as well but I'm sure that both will be in good shape. So it's difficult to pick any one person after effectively three days of testing, particularly when we haven't really put in any lap times and judged ourselves against them, but I think the impression we get doing the numbers and the homework appear to show it's going to be quite tight.
Key also didn’t make any predictions about the top half of the field, but expects Mercedes, Ferrari and Red Bull to be the three strongest teams come Melbourne.
"There's the top three teams that we traditionally have, it's difficult to tell at the moment because Ferrari do look pretty strong, Mercedes will be and I'm sure Red Bull will be as well. Whether there's a big gap between them and our group is difficult to tell but it's going to be very interesting next week when people really begin to focus on performance."
by Rachit Thukral