The Zodiac MkIII differed from its Zephyr counterparts in more than just engine size and trim level. Yes, there was the much bigger 2553cc six-pot engine, and yes, the car had more comfort to it, but its body was also substantially altered with more glass and slimmer roof pillars, a steeply inclined back window and an impressive chrome-laded front end characterised by four headlamps. Extra power over the Zephyr 6 meant 107bhp and a genuine 100mph. For 1965 to 1966, there was the Zodiac Executive which was pitched as a Jaguar rival.
info from Octane