The series quickly withdrew a shirt that stirred up a strong backlash. But IndyCar has been playing with fire for a whileThis could be the summer of IndyCar.Formula One fatigue is beginning to set in, both globally and among the American audiences who helped fuel the sport’s recent boom. Nascar, for all its national reach in the US and lingering cultural import, remains a largely regional attraction. IndyCar, on the other hand, boasts a wealth of personalities, is anchored in real structural par...