Ferrari is not serious when it occasionally threatens to quit Formula 1.That's the claim of McLaren team boss Martin Whitmarsh, who is also the chairman of the F1 teams' association Fota.He was asked about Ferrari president Luca di Montezemolo's recent warning that, without key changes to the sport, the red cars might pull out.'PASSION AND FRUSTRATION'Whitmarsh said: "I've been in this sport for more than 20 years and I've heard that said many times."I've never believed Ferrari would step out of the sport - I might be wrong, but that's my opinion. If you told me to take my pension and put it into two teams that will be here in 10 years I would put my money into McLaren and Ferrari."Whitmarsh thinks Ferrari's quit threats are often fuelled by "passion and frustration", and then exaggerated by the news media.He doubted McLaren would ever make a similar threat. "We would handle it differently because I don't think it does anybody any good. If you have a bad result, you're better off being determined to have better ones in future."