its not a maybe, it really was the reason given by the anime. the problem that s|lverfish and i had was that it didnt make much sense in real terms. u'd still have to drive just as fast as the guy in front to maintain a 6 sec gap, the only difference is that u cant see the fella. logic dictates that will make u less pressure and drive at ur own style (drive less harder?), but in the anime itself ryosuke states that keisuke will feel pressure from NOT being able to see the GT-R's backside.
maybe we're just not advanced enuff to understand, or this 6 sec hoolabaloo is just anime stuff that's better left as it is hehehe