Sebastian Vettel has said he is unconcerned by the FIA's decision to issue a clarification on engine mapping this week - and he believes it won't affect the performance of the RB8.

The rules have been revised ahead of Sunday's Hungarian Grand Prix and teams will now have to nominate any one engine map used in the first four races of the season as a reference map [see separate story - HERE].

While it is understood Red Bull will now have to make changes, the German doesn't think it is a big deal.

"There's probably more of a fuss outside the car than in it," he told ESPN.F1.com. "What we had on the car in Hockenheim was what we decided to go for because we believed it was quickest. It's a little bit different here, but it's hard to express [the difference]. It's hard to say two tenths, half a tenth or nothing because we can't measure it."

Speaking to BBC Sport, Vettel reiterated that he felt Red Bull will still be very competitive.

"It's not as if the car doesn't work any more. I'm quite confident nothing will change," he added.

Team-mate Mark Webber meanwhile is similarly unconcerned, at least publicly: "[The difference will be] very, very small, I would say," he continued.

"The guys haven't really even spoken to me much about it. It seems pretty tame on our side, so we will just get on with it."