Having previously suggested that Mercedes should be banned from further developing its engine in a bid to allow rival manufacturers to catch up, Toro Rosso boss Franz Tost now believes the time is fast approaching when all engine development should be frozen.

"It’s true that I said that the power unit that is on top should be frozen," he told the official F1 website. "In this case it is Mercedes.

"With the current regulations the development is totally free, which means that the costs for the power units will increase, because what makes it so costly is research and development.

"Currently we pay a high percentage of our budget for the power unit, and I think this should change in the future," he admits. "I can imagine that we could go the same route as we did with the V8.

"Of course, if there is a difference between the suppliers, those who are behind should be given the opportunity to close the gap. And if there is relative harmony, the whole development should be frozen.

"Right now we are on high level on the cost side and we should never forget that the cars and power units are just fabricated for a race on Sunday afternoon. So we should stay in reasonable limits on the cost side and work on the show, with sizzling fights among many different teams and great overtaking.

"In the long term it is not healthy if one team is so far ahead of the others," he adds, a view that is no doubt shared by sister team, Red Bull.

Of course, engines are something Tost knows about, Toro Rosso having changed supplier for the last three seasons.

"It is very difficult, as you are permanently confronted with new parameters," he admits. "The advantage for this season was that we knew about the change early in 2016, so we could react in time and the level of grief was much lower than in the previous years, as we had to design a new car anyway."

And what a car it is, even if the opening test didn't go entirely well.

"Yes, we look super aggressive," he admits, "partly also because our livery looks really sharp.

"When you look at the overall picture we should have all the ingredients to have a great season," he continues. "I assume our car is competitive - with Renault we have a good engine; we have competitive drivers; and the team has had stability in recent years. But in the end nobody really knows their position in the pecking order at this very moment. Four days’ running are simply not enough to have a final judgement."

Asked if he fears his team might lose out to Renault, which as well as supplying engines to its own team is also supplying the ultra-demanding Red Bull, Tost insists: "I hope we are all equals. We should receive the same parts and the same software. I am sure Renault will be fair enough to provide us with the same material the two other teams are using."

Check out our Tuesday gallery from Barcelona, here.