Ferrari president Luca di Montezemolo remains convinced that the "very grey" regulations relating to diffuser designs was the root cause of why former champions like his team, McLaren and Renault have all struggled this year.

"We now, after in the last 10 years winning eight titles in 10, now [Stefano] Domenicali and his group - together with some other teams - are at the moment not in the condition to win the championship," he said during a visit to Le Mans.

"But sometimes it is important to be hungry, because if you eat too much then you don't know what it means to be hungry. So sometimes in life it is good to be hungry and then when you eat again, you understand how the food is important. So after 10 years it's important sometimes and we will see.

"This happened because unfortunately we have been in front of very grey rules in which the interpretation of the rules was, how can I say, unpredictable.

"It's quite amazing that the teams that have won the last three world championship titles in Formula 1 - Ferrari, McLaren and Renault - has done the same interpretation of the rules.

"So it is one of two [reasons]: all of us became completely drunk, or the rules became not clear. I have the answer that this is not the case because we are not drunk, yet."