Why is Ferrari's Vettel so 'frustrated'

'He's obviously a bit frustrated with how the season's gone, he probably thought that maybe they had a chance to fight Mercedes but it hasn't worked like that.'

Sebastian Vettel's expletive-laden radio rants betray his frustration at Ferrari's fading form, according to his former Red Bull team mate Daniel Ricciardo and predecessor Fernando Alonso.

Four-times world champion Vettel turned the air blue in Sunday's Mexican Grand Prix, directing some of the abuse at Formula One race director Charlie Whiting in an outburst that some in the paddock compared to slapping a soccer referee.

It was not the first time this season that the German has let rip over the airwaves with bleeped-out swear words broadcast worldwide.

He called McLaren's Alonso, a double world champion who left Ferrari in 2014 when Vettel arrived from Red Bull, an 'idiot' in free practice at the Autodromo Hermanos Rodriguez  in Mexico City.

The Spaniard laughed off the insult by saying Vettel was "living a very frustrating period for himself and for Ferrari, so we have to forgive him".

Much of his ire has been aimed at Max Verstappen, Ricciardo's team mate, and he had plenty to shout about on Sunday after the Dutch teenager cut a corner while defending against Vettel and refused to give up the place.

Verstappen, who has annoyed plenty of other drivers, suggested Vettel go back to school to improve his language.

Ricciardo, who also clashed with Vettel and inherited third place when the German was demoted post-race, said his former team mate is under pressure.

"He's shown in the past he can be quite emotional but this year it seems to be a bit more," the Australian told reporters.

"He's obviously a bit frustrated with how the season's gone, he probably thought that maybe they had a chance to fight Mercedes but it hasn't worked like that."

Vettel won three races last year but Ferrari have drawn a blank in 2016 and been overtaken by Red Bull in the battle for second place behind Mercedes.

"Some things we've seen in the past, Seb gets a bit frustrated but it's probably been a bit more uncharacteristic this year, probably been a bit too much," said Ricciardo.

He said drivers have to be more sensible than just "squirting a whole lot of stuff" over the radio.

"Trust me, I would say twice as much," Ricciardo smiled. "But I do, a lot of the time, wait and maybe say a few things to myself and press the radio button.

"You don't need to broadcast it all. You can swear in your helmet and then speak your mind maybe a little bit more relaxed a few moments later."

Image: Ferrari driver Sebastian Vettel.

Photograph: Lars Baron/Getty Images

Lars Baron/Getty Images