That’s the verdict of Sauber chief Frederic Vasseur, who admits getting the four-time Formula One title-winners on-board would be impossible for his team.

Hamilton wrapped up the fourth World Drivers’ Championship of his career at Mexico City’s Autodromo Hermanos Rodriguez in October.

Vettel, meanwhile, has not won a title since 2013 but is among a band of just five drivers to have tasted glory on more than three occasions.

Bringing Hamilton and Vettel together has been talked of as an impossible task because of their on-track rivalry.

Vasseur has revealed he’d love to have the duo at Sauber - although he’s realistic about his chances of making it happen.

"The situation is not like this: this is not a picnic!" said Vasseur, when asked to name his ideal driver by Formula1.com.

"If it were I would say Lewis Hamilton and Sebastian Vettel – like any other team principal in the paddock!

"We have to be realistic: even if we move a good step forward next season we will not fight for wins.

"It took Red Bull Racing seven years before winning the championship – or five before winning a race – and the same goes pretty much also for Mercedes – and they even took over a team that were world champions!

"You can’t be faster than this – good things need time.

"Having said that, we need drivers that will fit to our plans.

"The worst-case scenario for us would be having someone who dreams about being world champion next year!"