mrluke wrote:If downforce increases with turbulence then the current cars should have a pretty similar difficulty in overtaking during the current era and the 80s. We know this is not the case therefore it must be something other than "turbulence" that is the main reason for decrease in overtaking.
I assume you mean: If turbulence increases with downforce............?
I have already posted my opinion on why this may be the case (complex aero interactions), though I'm no aerodynamicist.
I'll repeat what I said before. In the past cars could follow a lot more closely than today and overtake with half a seconds pace advantage over the car ahead. Today a car can be over 1 second a lap quicker, have access to DRS and still be unable to pass.
In the last few days, I watched the 1991 Mexican GP, 1991 German GP, most of the 1993 British GP and parts of the 1993 Portuguese GP. It is abundantly clear that cars could follow more closely back then and that includes team mates driving the same cars (which rules out variations in car performance as a factor).