[bcrdukes]

I would assume that driving habits may contribute to carbon buildup and perhaps there is a correlation that may suggest additives in top-tier fuels help prevent, or rather, slow down carbon build up. We can assume someone in say Richmond who drives five minutes to the store has barely warmed up their engine, so the rich mixture when driving cold doesn't help the situation. (Not directed at you, Badhobz.)

And then you have bore scoring from Porsches. *yawn*