Rode today inspite of the call for scattered showers. About 75 miles into my trip, on HWY 521 south of Kershaw, SC I heard a low growling noise and then gone. Listened to the front end, speakers (raido off), heard it again. This time I thought I had been overflown by some type of aircraft??? cloudy could not see anything. Then again, this time off to my right?? About this time I come upon, Carolina Motorsports Park, turn in talk to the gaurd. So happens, all of Hendrick Motorsports Cup drivers, Gordan, Martin, Johnson and Earnhardt jr., plus Kyle Bush were there practicing. A few turns come really close to the highway so their cars were what made the strange noise. Can't see much of the track from the gate maybe 5 turns and the pit area. Still pretty cool to listen and watch what I could. This place is open to the public, car clubs and to anyone with a car that he/she wants to put on the roadcourse track. After a fee, a waiver and some school time., of course. carolinamotorsportspark.com Cool noise, and it was'nt my scoot!