I saw something like this when I was coming home from Miami last year. There was a police escort with 2 helicopters over top on Alligator Alley. There was over 50 Lambos, Ferarris, Porches, etc.. They were all hauling ass (at least 100mph) and I followed behind them all throughout Alligator Alley. I even got it on video..

When I got home I did a little research and found out it was the yearly "South Florida Super Car Run".