F1: Renault progress clear to Toro Rosso on return

The progress made by Renault over the past 12 months has been made clear by Toro Rosso's year away from the French manufacturer, according to technical director James Key.

Toro Rosso ran a Renault power unit in 2014 and 2015 but a lack of performance and reliability resulted in Red Bull looking to end its deal early. The junior team picked up a supply of year-old Ferrari power units for last season, while Red Bull itself eventually had to remain with Renault – branding the engines TAG Heuer – and duly won two races.

With Toro Rosso returning to Renault for 2017, Key says the break in the partnership highlights just how much the power unit has changed over the past year.

"Yeah very much so," Key told RACER when asked if he had noticed a big difference in Renault's power unit and architecture compared to 2015. "I think they've turned a tricky situation that they had when we had them previously into a much more coherent, robust approach.

"They've definitely made very real progress. The power unit architecturally is different, it's a much tighter installation as well now. The sort of feedback and information that we're getting from them is positive and all well understood and we're working very well from them. So I think they've definitely turned a corner from last year and that trend from what we can see at the moment is continuing I think."

The gap between Toro Rosso's power unit performance and the rest of the field grew the longer last season went on, but Key says the rekindled Renault partnership gives him further confidence the team can achieve its target of fifth place in the constructors' championship.

"The good news is we will have the most competitive engine we'll ever have had since the power units came in with the new Renault. They're looking much stronger than they were when we last worked with them, and there's no doubt that it's an engine which will develop well as well, so we're looking forward to that.

"We've got a couple of drivers we know well – they know what to do, so there's no driver training requirement for the coming year. It's really up to us to make sure we put a chassis on the track which is as competitive as it can be."