Between 1969 and 1974, Jaguar’s E-Type went through more change than any four-year stretch in its history — detuned engines for U.S. emissions rules, a completely new V12, and a dozen ultra-rare lightweight racers built alongside the roadgoing cars. The Series III’s 5.3-liter V12 turned the E-Type into a genuinely different machine, capable of 135 mph and a 14.82-second quarter mile. Read on to find out what separates a Series II from a Series III, and why twelve specific cars from 1963 and 1964 remain the most valuable E-Types ever built.