MkIV : The Spitfire MkIV had a fresh new look, with a distinctly restyled front and rear and a smart new hardtop.

In 1970, Triumph came out with what can be called an almost complete re-skin of the Spitfire, executed by the Spitfire's original designer Michelotti. The front was cleaned up, losing the trim strips on top of the bonnet and the chrome headlamp surrounds. A black plastic grille and black plastic bumper underrider covers were added.

The doors were fitted with more modern, flush-fitting handles and the wheelarches were flared slightly. The windscreen's height increased by 2"/50mm and its frame became an integral part of the scuttle construction, so it was no longer removable by simply unbolting it. The styling of the rear was brought into line with other Triumph models like the Stag and the 2000 saloon. This also brought slightly improved boot space. The rear bumper now came in one piece, instead of the previous two small bumpers on the corners. The only outer panels to remain completely unchanged were the sills.

Triumphs own stylists came up with a smart new hardtop, with a much flatter roof panel than the previous bulbous offering, opening rear quarterlights and a flat rear window. The hood frame of the softtop was partly covered by black plastic moldings, in an effort to prevent injury to the occupant's heads.

Designer Michelotti had proposed popup headlights, as seen here on a prototype MkIV. It didn't happen because of high production costs and the fear that these would soon be outlawed in the US.

The dashboard was of the type that had already been introduced in the 1969 Mk3's for the US market: black plastic, with the main instruments in front of the driver, instead of in the middle. Later in its production life, a wood-veneered dashboard was fitted. At last, black padded sun visors, safety belts and a heater came as standard on all markets. Cars fitted with overdrive now had a sliding switch on the gearknob instead of a lever on the steering column.
The MkIV basically had the 1,296cc engine from the Mk3, but to simplify parts manufacture and supply it was fitted with the larger conrods of the six-cylinder engines.
Contrary to popular belief, the MkIV engine was not detuned form the start. Initially, its quoted output was 63HP, as opposed to the quoted output of 75bhp for the Mk3 engine. The only difference was that the 63HP was a result of measuring according to the German DIN system - actual power output was no different.
Still, the MkIV was slower than the Mk3, due to higher weight, a taller final drive (3.89:1 as opposed to 4.11:1) to improve fuel economy, and a new gearbox with a taller first gear (which, incidentally, was now synchronised).

At last, a major design weakness in the rear suspension was properly dealt with. Handling in corners of previous Heralds and Spitfire models had been 'interesting', with dangerous tuck-under of rear wheels easily achieved. This was caused by the transverse rear leaf spring assembly being bolted solidly to the top of the differential casing.

Thanks to a simple modification of the rear axle, handling of the MkIV was much improved.

The solution of the Triumph engineers was both effective and cheap: just the bottom leaf of the assembly remained fixed to the differential casing, but the others were free to pivot around a central axis. This transformed the handling of MkIV Spitfires compared to earlier models. Finally, Spitfire drivers could throw their cars about without the danger of being launched into the scenery. Wire wheels were still an option, but they were no longer of the centre-lock type, but of the much simpler and cheaper 'bolt-on' variety. Later on, the rear axles were lengthened by 1" (25.4mm) each, improving roadholding.

Top speed of Euro-spec MkIV's was 97Mph (155km/h) and 0-60Mph (0-96km/h) took about 12.5 seconds. From 1972, a slightly detuned engine was fitted, lowering the numbers to 95Mph (152km/h) and a disappointing 14.5 seconds.

Note: previous marks of Spitfire were called Spitfire4, Mk2 and Mk3. The MkIV was not designated Mk4 to avoid confusion with the original Spitfire4.