With demand for the Mark III stuttering gradually to a halt, it is possible that Ford may have lightly pressed on the panic button. The result of their panic was the launch of the Mark IV version of the Ford Zodiac. . .

Their timing coul have been better. with the launch coming early in 1966, when demand for new cars were at their weakest- at the peak of a typical UK winter.

The marketing team at Ford UK, always supremely confident in their ability to market any model that came out of Dagenham, but were even more so with the Mark IV, which was a very imposing vehicle, at least physically.

With a much stronger North American design slant than any other Ford UK model, the new  Mk IVs were bigger, heavier and less wieldy than anything that had come before in the  Zephyr/Zodiac sector,  larger than the Mk Ills, that had also been a lot bigger than the Mk Ils.

To most observers, from the most professional to the most casual, the Mark IV was lacking in proportion, with a broad and ultra-long bonnet and a rather truncated tail. The Mark IV platform had a 115in wheelbase (eight inches longer than the Mk III).

While this design style made for more than ample cabin space for five passengers, it came with a price, with handling problems, especially in the early versions, an issue. 

On the other hand, on the open road, thanks to the power of Ford’s 2,495 cc (152 cu in) V6 unit fitted on the Mark IV, driving was a pleasure. The Zephyr came with the choice of a 1996 V4 or 2495cc V6 engine.

The famous Essex V6 was used in the plusher Zodiac and deeply luxurious Executive, which came fitted with the 2994cc Essex V6, a few Zodiac variations also shipped with this massive and ultra-powerful power plant.

As well as its engine, almost every major component was new, including independent rear suspension and a new Ford automatic transmission, as well as with MacPherson strut front suspension and semi-trailing link independent rear.

Other technical innovations to first appear on the Mrk IV were with four-wheel servo-assisted disc brakes while power steering came as standard, initially on cars fitted with the up-market Executive version, but soon in all of the variations due to the manoeuvrability problems that were being reported by new owners.

Recognition soon became clear of the reason for the car being so front heavy was not only because of its massive engine but also by Ford's almost unexplainable decision to place the spare wheel under the front bonnet. 

Another method employed to deal with increasing criticism of the IV's handling ability was fitting radial-ply tires on the larger-engined version in place of the more conventional cross-ply tires, standard when the car was launched.

This step was  aimed towards addressing the alarming tendency of the model’s rear wheels to slide uncontrollably in wet weather and turned out to be very efficient, especially when Ford's new and sophisticated rear suspension began to be fitted on the Mark IVs.

The Zephyr/Zodiac Mark IV could be counted as among one of Ford UK's least successful launches of the Sixties, with not a lot going for it technically as well as eye appeal.  On the other side as far as driver and passenger comfort, the Mark IV was undoubtedly among the top cars produced by Ford in the UK.

Around 150,000 Mark IVs were sold before the model was discontinued in 1972, replaced by the Granada, which was much of the same but with a  more well-rounded  European look to it.