The Rover P4 series was a group of saloon automobiles produced from 1949 through to 1964 designed by Gordon Bashford. The P4 designation is factory terminology for the group of cars and was not in day-to-day use by ordinary owners, who would have said simply that they had a "Rover 90" and so on.
The P4 was also the basis of the short lived Marauder car. The P4 was also the basis of the short lived Marauder car.
The cars used a Rover engine in 4- or 6-cylinder form which came from the 1948 P3 and had overhead Valves for inlet and side Valves for exhaust. A four-speed manual transmission was used with a column-mounted shifter at first and floor-mounted unit from 1954. At first the gearbox only had synchromesh on third and top but it was added to second gear as well in 1953. A freewheel clutch, a traditional Rover feature, was fitted to cars without overdrive until mid-1959, when it was removed from the specifications, shortly before the range rearrangements announced for the London Motor Show in October that year. The cars had a separate chassis with Independent suspension by Coil Springs at the front and a live axle with half-elliptical leaf springs at the rear. The brakes on early cars were operated by a hybrid hydro-mechanical system but became fully hydraulic in 1950. Girling disc brakes replaced drums at the front from 1959. The complete body shells were made by the Pressed Steel company and featured aluminium/magnesium alloy (Birmabright) doors, boot lid and bonnets until the final 95/110 models, which were all steel to reduce costs. The P4 was one of the last UK cars to incorporate rear-hinged "suicide" doors..
The P4 90 was not to be the top of the P4 line. Introduced in 1956, the P4 105R and P4 105S used a high-output, 8.5:1 compression (to take advantage of the higher octane fuel that was by then available), version of the 2.6 litres (160 cu in) engine also used in the 90. This twin-SU carburettor engine produced 108 hp (80 kW). Both 105 models also featured an updated exterior, the 105S featured separate front seats, a cigar lighter, chromed wheel trim rings and twin Lucas SFT 576 spotlamps. To minimise the cost of the 105R, these additional items were not standard, however they were available on the (higher priced) 105R De Luxe.
The 105R featured a "Roverdrive" automatic transmission. This unit was designed and built by Rover and at the time was the only British-built automatic transmission (others had bought in units from American manufacturers such as GM). This unit was actually a two-speed automatic (Emergency Low which can be selected manually and Drive) with an overdrive unit for a total of three forward gears. The 105S made do with a manual transmission with overdrive, but could hit 101 mph (163 km).
The Motor magazine tested a 105R de luxe in 1957 and found it to have a top speed of 93.9 miles per hour (151.1 km/h) and acceleration from 0–60 miles per hour (97 km/h) of 23.1 seconds. A fuel consumption of 23.6 miles per imperial gallon (12.0 L/100 km; 19.7 mpg-US) was recorded. The test car cost £1696 including taxes of £566.
When production of the 105 line ended (in 1958 for the 105R and 1959 for the 105S), 10,781 had been produced, two-thirds with the manual transmission option. For 1959 the manual model was described simply as a 105 and the trim and accessory level was reduced to match the other models.
Also see: Rover Reviews | The History of Rover