Triumph TR5 vs TR6

The TR5 was the TR4A with a six-cylinder engine, and the TR250 the same with carburettors. Around the engine came smaller changes, as Motor Sport, Aaron Severson and the German TR Register's guide record:

The live axle that some American TR4As had was dropped: every TR250 had independent rear suspension, as every TR5 did. Revington TR lists changes out of sight too: the bulkhead, the doors and their winders, the outer door handles, which were shared with the MGB, the front valence and the rear floor, the steering's position on the frame and the differential's mountings. The German guide calls the bodies "weitgehend identisch" (largely identical, in our translation), the differences being lamps and the inner wings (fenders) for four or six cylinders. The two-piece hardtop and its Surrey top carried over.

The TR5 came out a little heavier than the TR4A: by 13 kg (28 lb) in William Krause's history, and by 29 kg on the kerb weights in the German guide. Neither says what was weighed, and the difference in the amount stands.

Severson dates the decision to restyle the body, the TR4's of 1961, to mid-1967, before the TR5 reached a showroom: it needed an update "post-haste". With Michelotti busy, Karmann redrew the front and the rear, and the TR6 kept the rest, as the table shows. Severson's verdict is in a caption:

The TR6's wheels were wider, 5½ in, and the VTR adds that its Laycock A-type overdrive came from the TR250's gearbox. In Britain the TR6 PI started at £1,020 before tax, £1,333 19s 2d with it, which Severson makes £35 more than the TR5's basic price of spring 1968. In America the TR6 started at $3,275 at the port of entry, by his account a bit cheaper than the TR250 had been at its launch. The performance, he writes, was little changed: Road & Track's TR6 of 1969 was "almost dead even with their previous TR250 up to 100 mph".

Two other ideas for the next TR appeared early in 1968, and neither was taken up. Giovanni Michelotti's TR5 Ginevra, built in 15 days on a TR5 chassis for the Geneva show in March, was in tr5passion.com's account his proposal for the next TR, the evolution of the TR5; the TR6 was Karmann's all the same.

In America, Kas Kastner and Peter Brock built the TR250K for the Sebring 12 Hours of the same month, a body Brock drew on what Kastner called the TR4A chassis, with the TR250's six, and proposed it as the basis of a future TR. Kastner put it on magazine covers to win support, but, Severson writes, "Nothing came of it", and according to him Bruce McWilliams, who had authorised it, held that it could not have gone into production without being diluted.

Severson also describes an earlier idea, the Fury of 1964: a smaller, Michelotti-styled six-cylinder prototype with a body that carried its own loads, which he presents as a logical next step, though a new body structure was "not yet feasible" while Leyland's resources were committed elsewhere.⁠source 18​source 19​source 1​source 20​source 21

The injected six had a second home. Triumph's 2.5 PI saloon (sedan), announced late in 1968, used the same engine and the same Lucas Mk II injection, in milder tune: Bill Boddy, driving one for Motor Sport in 1969, gave it 132 bhp at 5,450 rpm, and Severson notes that its torque peaked much lower in the engine's range than the TR5's. Boddy's description of the engine leaves no doubt of its origin:

By Severson's account it was the saloon, not the sports car, that sold the injected six in numbers: more than three for every TR5.⁠source 22​source 1