By Madeline Coleman Racing fever swept South Florida last weekend as celebrities such as Serena Williams, James Corden and Tom Brady filled the paddock. The sport’s drivers, meanwhile, saw room for improvement. MIAMI — Close your eyes. Imagine the Florida heat in May, the slight breeze as the afternoon storms roll in and sun beating down. You’re walking through the crowded paddock, shouldering your way past Michael Jordan, Serena Williams and David Beckham as they try to make their way to the garages. You hear the roar of fans in the distance, nearly drowning out the sounds of Formula One cars…