Vettel says mule car not a fair reflection of 2017 downforce

Vettel has been one of the drivers in charge of carrying out testing duties for the tyre manufacturer, using a 2015 car fitted with skirts and a bigger rear wing to simulate next year's downforce.

However, Pirelli has already expressed concerns that the downforce levels are around 20 percent short of what it actually needs and is in discussions with the FIA to try to find a solution.

Vettel said the grip levels with the wider 2017 tyres did not feel much higher than with the current rubber.

"You need to speak to Pirelli, obviously. With the tyre testing we are a bit blind," said Vettel. "We get to test different tyres and then we give our feedback.

"I think Pirelli is still in the early days and there is still a lot of change so I'm quite keen to find out the last test in Abu Dhabi, which I think it's probably closer to what we'll have next year, but even from then to next year I think there will be some changes.

"I think the tyres in terms of grip are fairly similar to what we have now, probably a little bit better, but I think the interim car is also not entirely fair.

"So a lot of it is still blind but to get a first idea I think it's heading in the right direction, but for details you'd have to speak to Pirelli as they are not giving us much information."