This car has stock SU carburettors - the torque is much less compared to a P6 fitted with an aftermarket four-barrel racing carburettor - which is what I am used to.
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https://www.youtube.com/watch?v=jjlbWvpQuIM
A 1970 Rover 3.5 Litre Saloon, DPK797J shows that she has no difficulty keeping up with modern traffic as she completes an anticlockwise lap of Manchester's M60 orbital motorway with ease.
This footage starts at the Shell on the A57 Regent Road - heading first out on the M602 then back into central Manchester along the same road.
This section is from Junction 15, the start of the Worsley Braided Interchange to J2 of the M602. We pass J14, the exit for the A580 East Lancs Road. We take a left-hander at the Eccles Interchange to head back into Manchester along the M602.
The sound was recorded with the built-in microphone - even by modern standards the P5b is a quiet car.
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https://www.youtube.com/watch?v=IIfGVxtZOnA