WHILE DRIVING AT APPROX. 45-50 MILES PER HOUR, THE SUNROOF OF OUR AUDI QUATTRO ALLROAD EXPLODED. THERE WERE NO PRIOR IMPACTS, DINGS, CHIPS, CRACKS ETC IN THE SUNROOF. IMMEDIATELY PRIOR TO EXPLOSION THERE WAS A HOLLOW-SOUNDING POP. THE DRIVER WAS SHOWERED WITH GLASS WHICH HAD TO BE REMOVED FROM ARM, NECK AND HAIR. INCIDENT OCCURRED IN ALTITUDE AT TEMP. AT OR ABOVE 100 DEGREE. *NM