Auto was probably in overdrive, from 60mph the first thing that happens is you double-kick down into 2 and revs instantly rise to about 6k - well out of the boost range - you then rev the nuts upto redline until it changes up to 3 and you get some proper boost. So 2 car lengths yeah - if the above happened.
Oh - and by the way, in 3 at 60mph with O/D off, you are at about 3k revs, right in the sweet spot for instant boost at 4k
I may be slightly wrong with some of the rev ranges etc, but I do know this, if I'm cruising in traffic at 60mph, when the road clears and I want to take off, I need to have O/D off or when I kick down it sounds like the poor engine is chewing glass [sHOCK][/sHOCK] and I get no acceleration.
Just my take...