We were already fans of the P6 V8, but it was hamstrung by a mandatory torque-converter auto. The S model’s manual ’box perfected the recipe.
The four-speed manual gearbox from the 2000 was strengthened for the 3500S and a revised exhaust system slightly increased power over the auto. The manual, like the auto, used two SU carbs to feed its aluminium-intensive V8.
Losing the torque converter greatly increased throttle response without sacrificing smoothness and flexibility, although transmission whine irritated. A comfortable cruising speed was 100mph despite some wind noise, and economy impressed, too. All-round disc brakes performed well.
The supple ride was in line with the 3500S’s overall refinement and variable-ratio steering worked nicely. Roll was quite pronounced and the car generally understeered but it could be coaxed into a controlled powerslide.
Seating was nicely adjustable and supportive, and the instrumentation excellent. Fit and finish was superb both inside and out, and a narrow boot was our only interior complaint.
For: Performance, economy, ride, build quality
Against: Noisy transmission, wind noise, cramped boot
What happened next...
The four-cylinder P6 jumped from 1978cc to 2205cc in 1973 in the 2200SC (single carb) and 2200TC (twin carb) models, making 98bhp and 115bhp respectively. They continued production next to the V8s until 1976, by which time British Leyland’s build maladies had taken their toll. The P6 was replaced by the SD1, which kept the 3.5-litre V8 but reverted to a live rear axle.