guys why going in so much detail.....the answer is simple it is possible and not possible also.....
the recommendation given by JK will do the job but on a condition that there is no ambeint noise there so that one can easily judge from where the sound is coming.....but normally this does not happen so I think
abhibh leave the thougth of showing off at a distance of 500 meters or 200 meters...it is highly impractical......
here is a simple calculater from which one can see how much sound reduces with the increase of distance....
http://www.sengpielaudio.com/calculator-distance.htm
Like u have a 120 db source in your car....with a distance of 200 m the sound level would reach at 73.98 db which is a very big change....and if one is standing at a crowded area or even at a intersection there will be many 73.98 db sound sources...so it will be hard to pin point from where the sound is coming to make a statement.....
to achive such high SPL in car is not a easy job one need right equipment to achive it....Even I am behind many.........