The Rover 90 and Rover 105 were replaced by the more powerful 100 announced on 24 October 1959. Its new but similar 2.6 litres (160 cu in) IOE straight-6 engine was a short-stroke version of the P5 3-Litre unit. The 100 could reach 100 mph (161 km/h). The interior was luxurious, with wood and leather accents on traditional English car elements like a curved "Shepherds Crook" handbrake lever. A bench front seat or individual front seats could be ordered. A heater was a standard fitting. Like the smaller 80 version, the 100 was fitted with servo-assisted Girling disc brakes at the front, keeping drum brakes at the rear. Overdrive, on top gear only, was a standard fitting.
Production ended in 1962, by which time 16,521 had been produced.
Testing the 100 in 1960, The Motor magazine recorded a top speed of 92.1 miles per hour (148.2 km/h), acceleration from 0–60 miles per hour (97 km/h) of 17.6 seconds and a fuel consumption of 23.9 miles per imperial gallon (11.8 L/100 km; 19.9 mpg-US). The test car cost £1538 including taxes.