(145 km/h). It has a cast-iron block with an aluminium alloy head, a bore and stroke of by and a 6.73:1 compression ratio. This was upped to 7.5:1 in 1956. Rover's stated intention was to cater for a wider field of motorists requiring varying degrees of performance and running costs. The Rover 90 shared with the Rover 60 and Rover 75 the October 1954 modifications: a bigger boot, wide rear window and flashing directions indicators all announced at the Paris Motor Show. The 1956 model was launched in September 1955. Independently adjustable separate front seats were made available at extra cost and at the same time the engine's compression ratio was increased from 6.73:1 to 7.5:1, lifting power by 3 horsepower to 93. Free-wheel was dropped and Laycock de Normanville electric overdrive made available. More sensitive power brakes were provided of a redesigned pattern. The recesses in the 'B' pillars that previously housed the trafficators in pre-1955 models were deleted in this update. Pleats were added to the seats, this treatment continued on subsequent P4 models. In September 1956 the shape of the front mudguards was rearranged with the side lamps and flashing indicators in different positions. A small chrome reflector on the headlamp rim allowed the driver to know the side lights were functioning. Testing the Ninety in 1954 The Motor magazine recorded a top speed of and acceleration from 0– of 18.9 seconds. A fuel consumption of was recorded. The test car cost £1297 including taxes. A road test of a Ninety published in MotorSport magazine in September 1956 described the engine as virtually inaudible when idling but the steering was "spongy and heavy" and "the roll when cornering was considerable" nevertheless, reported MotorSport, firm suspension caused "very appreciable column shake and body judder". When it was replaced by the Rover 100 in October 1959, 35,903 had been produced, making the Rover 90 the most popular car of the P4 series. Rover 105R, 105S & 105 Announced on 16 October 1956, the 105R and 105S used a high-output, 8.5:1 compression version of the engine used in the 90. The higher compression was to take advantage of the higher octane fuel that had become widely available. This twin-SU carburettor engine produced 108 hp (80 kW). Both 105 models also featured the exterior changes of the rest of the range announced a month earlier. The 105S featured separate front seats,