Sebastian Vettel has defended his habit of changing his Formula 1 helmet livery - and scorned Twitter.The double World champion uses several designs in a season and that, according to Germany's Auto Motor und Sport, is "a bit disappointing" in the eyes of some spectators.BEAUTIFUL HELMETS"Is it (your livery) not your business card, something special?" the magazine asked Vettel in an exclusive interview.Vettel answered: "Some things on my helmet always stay the same but somehow it just happened that my helmet designer and I experiment and have fun with it. Together, we usually have pretty good ideas."I do find some helmets incredibly beautiful," the 24-year-old German conceded. "Like Senna's. Or the bars on Damon Hill's black helmet. Or the Scottish (St. Andrew's) cross on David Coulthard's. Very simple but unmistakable."Vettel may be setting a trend in one way but on the other he has so far resisted joining the new age of Facebook and Twitter."For me, this is not real communication. It's not my thing," Vettel insisted. "I find it a very indirect and impersonal way to communicate with other people."