First in a long line of high-performance factory 'specials' was the EH 'S4' which again through light weight proved competitive in the 'Improved Production' class against the big twin-cam Jaguar 3.8 litre Mk2s and early Mustangs of the day. S4 improvements over regular EHs included a forged crankshaft, factory-blueprinted head, heavy-duty drivetrain etc.
With similar mods to what was seen in warmed-over street cars of the era, this EH S4 below hit 130mph, again at Bathurst