The E-Type cars with V12's were a great combo -- but they had those four god-awful Zenith Stromberg carburetors and never moved to fuel injection. Unfortunately the E-Type never was able to get fuel injection. Jaguar did put it into its successor though -- the XJS.
That said, if you were savvy enough, or had a mechanic that was able to properly synchronize and tune those four carburetors, the 5.3L V12 was one of the smoothest running engines ever produced. It literally was better than anything in it's class. Unfortunately, not too many mechanics were able to do the engine justice because the carbs required a master's touch. At the time, I only knew two guys in my area that could tune the V12 properly -- and they literally were stars in the local Jaguar community.
