Rosberg: Fatigue could cost drivers race wins in F1 2017

The German retired from the sport at the end of last year after securing his first F1 drivers' title for Mercedes, right before the regulation change that has made cars faster and tougher to drive.

While he called time on his career before getting to try the new machines - although he did complete a Pirelli tyre test with a Mercedes higher-downforce mule car in Barcelona - Rosberg has now praised the direction F1 has gone in with its rule changes.

Rosberg, present during F1's opening week of 2017 pre-season testing at Barcelona, told media: "It's such a massive hype at the moment. So I wanted to see it first hand as well, see the new cars. They look absolutely monstrous, very very aggressive, and everybody's excited and that's great to see.

"The drivers are loving it, and I think this year they will be proper gladiators out there, with these cars. Because the cars will take them to their physical limits.

"We might even see drivers losing race wins because of just being 'game over' physically - and that's what we need."

Asked whether the excitement of the new cars and the strong form of Mercedes made him at all regret the decision to retire at the end of 2016, Rosberg moved to brush off any such suggestions.

He said: "I expected [Mercedes] to be the best this year, because the team is awesome, yeah? I am not saying that that's the case, we still need to wait and see, but for sure it looks like they've done a great car - but that's not surprising.

"I'm really happy with my decision, you know, and I still love the sport, so it's great to be here, great to follow the action.

"The positive hype is awesome at the moment, you know, and I really hope the sport can progress, that would be cool.

"It feels good [being here], it's just very different, I'm very relaxed, I'm enjoying it. I'm very happy with the way things are going and looking forward to the future."

Additional reporting by Jonathan Noble