Jaguar XK150 In May 1957 the XK was revised dramatically for the last time as the XK150. Introduced at first in drophead and fixed head forms, it was bigger and heavier than its predecessor, but a good deal faster in the middle range of its performance. Fitted with the new B type cylinder head, it no only developed 190 bhp, but also gave the engine a lot more mid range torque. The C type head was still available for ultimate top end performance. Almost as soon as the XK150 went into production it was fitted with disc brakes all round which like the C Type on which they were pioneered - made the new car much faster from point to point.
The chassis and running gear of the XK150 were substantially the same as on the XK140, but the coachwork looked very different. The body was given a raised waistline with bulbous doors and wings to allow the interior to be widened by 102 mm, giving more room for the occupants, who also benefited from a further raising of the scuttle line. Like the Mark VIII, a wrap around windscreen was also fitted now that glass of the right quality was available, and the fixed head coup was given a large saloon style rear window to make it feel more spacious. Other changes to the body included wrapping the bumper around the flanks for greater protection, and fitting a wider radiator grille for improved engine cooling.
In March 1958 the XK150 roadster was introduced. Being a lighter car it was faster, even more so when it was fitted with an option straight port cylinder head and triple carburettors, which increased the power to 150 bhp. In this form it was known as the XK150S. The brakes were also improved by fitting square quick change pads developed on the D Type in place of the older round type.
In October 1959 an enlarged engine was offered on all XK models: the 3.8 litre unit which had been under development by the factory since it was first use on a D Type in 1956. The bore was increased to 87 mm in a new block with dry liners.
Available in several configurations, the top of the range XK150S 3.8 litre as it was known, produced 165 bhp with a 9:1 compression ratio straight port cylinder head and triple SU carburettors.