Toro Rosso's technical director James Key says the Renault engine used in his team's car has made a big step in terms of performance this year.
Although Toro Rosso got off to a slow start during the first week of testing with reliability problems and a best lap time that was over three seconds off the pace set by Mercedes, the team is still targeting a strong position in the midfield this season. After using a year-old Ferrari power unit last year, the switch to Renault power should help the team move up the grid and Key said he has been impressed by the figures he has seen from the engine so far.
"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."
Key believes the battle in the midfield will be very tight behind the big three teams.
"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.
"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.
"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."