It’s hard to imagine that what was probably the greatest range of post-war production sports cars, really started life as an engine looking for a suitable chassis/body unit.
The story of how Jaguar’s XK engine was devised, during wartime factory fire-watching duties, is well known, although the DOHC straight-six wasn’t designed for a sports car, rather for the first Jaguar sedan destined to be created once hostilities had finished. William Lyons didn’t want Jaguar to be caught napping without a new post-war car, and the best place to start was with a new engine. It was destined for the Jaguar Mark V, but the preparation of the car lagged and it was decided to launch the new engine in a limited-production sports car.
So, a single Mark V chassis was suitably modified and a prototype Jaguar XK120 was unveiled at the 1948 Earls Court Motor Show. To say the XK120 stole the show is an understatement, and it caught Jaguar by surprise, as at that stage there were no plans for a production run. However, the motoring public had a different idea and the orders came flooding in. The first Jaguar XK120s were constructed by the traditional method of aluminum over an ash frame, but it wasn’t until May 1950 that production commenced on the steel-bodied cars.
Initially, the XK120 was only available in open form, or to give it the full title, the Jaguar XK120 Open Two Seater Super Sports. Then, in 1951, Jaguar introduced the XK120 Fixed Head Coupe and two years later brought the release of the XK120 Drophead Coupe, which had the same luxurious interior as the Fixed Head Coupe, but with a lined and padded folding soft top.
The capacity of the XK engine for the Jaguar XK120 was 3,442-cc, developing 160 bhp and driving through a four-speed Moss gearbox. This provided a top speed of 126 mph, with drum brakes all round to bring it back to a standstill.
On a Roll
A few years into the 1950s and Jaguar was on a roll. With a new small saloon in the wings, the Jaguar sports car received a revamp in 1954 into what was called the XK140. Again available in the same variants—roadster, drophead coupe and fixed head coupe.
To the uninitiated, the XK140 looked the same as its predecessor, but it was in fact three inches longer, mainly due to the larger bumper bars necessitated by the U.S. market. However, there was more internal room due to the introduction of rack and pinion steering, which allowed the engine to be placed farther forward, which in turn also permitted the front bulkhead to be moved farther forward.
While engine capacity remained the same, the power was up to 190 bhp, which provided for a slight increase in top speed to 129 mph. For those who wanted a little more performance, a highly efficient cylinder head, as fitted to the Jaguar C-Type, was available, along with larger SU carburetors. The Moss gearbox remained the same, but a Laycock de Normanville overdrive was offered as an option.
Progression
Then, and now, the introduction of the Jaguar XK150, in May of 1957, was seen by many as a natural progression for the model. To the untrained eye the new model would have looked exactly the same as its predecessor, but there were myriad changes, both subtle and significant. Interestingly, only the coupe and drophead coupe were available for sale at first, and it wasn’t until March of 1958 that the roadster was actually introduced.
The big change under the metal was the introduction of four-wheel disc brakes that coincided with the same fitting on Jaguar’s new 3.4-liter compact sedan. Also available for the first time was the optional Borg-Warner DG three-speed automatic transmission. The manual gearbox remained the Moss four-speed, along with an optional overdrive. Initially, motive power came from the same 3.4-liter, DOHC, 190 bhp, straight-six that was fitted to the XK140, but buyers had the opportunity to opt for the more powerful 210 bhp SE engine.
Jaguar fanciers of the time would have thought that the XK150 was a bigger car, because it looked like it was. However, while it was just one inch longer, the width and wheelbase were the same as its predecessor. Despite there being no real changes, cabin space had been increased, brought about by alterations to the doors and front guards that made them more vertical. This allowed for an increase in both shoulder and elbow room for the occupants. Gone in the cockpit was the use of wood, as all XK150s were fitted with the same style facia covered in padded grey leather, while the top of the dashboard was also in padded leather. Similar fittings were also included on Jaguar sedans of the period.
Coinciding with the introduction of the Roadster model was an optional new cylinder head that, when ordered, also came with larger carburetors and revised manifolding. Called the XK150 “S,” this new engine developed 250 bhp at 5,500 rpm and initially was only available with the Roadster.
In October of 1958 Jaguar introduced the new 3.8-liter engine for its Mk IX saloon and it was only a matter of time before the larger engine would be made available for the XK150 in all three variants. This occurred toward the end of 1959, and in standard form the 3.8 engine would deliver 220 bhp, with 265 bhp available in “S” form. In the latter iteration, a Jaguar XK150 “S” is good for a maximum speed of 135 mph.
By mid-1960, the days of the XK150 were numbered, and the last was built in October of that year, with its successor, the E-Type, launched in March 1961. In total, 9,385 Jaguar XK150s were built.
As can be seen, Jaguar XK150s command quite reasonable money, the amount, of course, being determined by condition. If your heart is set on a restoration project, you have to set your budget at the low to mid-twenties just to start with, but as with many Jaguars, the XK150 is not the most economical car to restore. So, as with most things in life, you really get what you pay for.
Our sample Jaguar XK150 is a 1958 Coupe fitted with the 3.4-liter SE engine (developing 210 bhp) and the four-speed Moss box with Laycock de Normanville overdrive. So fitted, it was found to be a very easy and enjoyable drive with more than ample power. Despite all the brickbats heard about the Moss box, we found that while it wasn’t a slick change, it matched the engine perfectly.
With its closed bodywork there was, of course, no wind buffeting, and with its long legs and very comfortable seating and cabin it was clearly built with long-distance touring in mind. Surely, the classic British sports tourer of the 1950s, built for the then burgeoning U.S. market.
Driven Classics at a Glance:
SPECIFICATIONS
Production 1957 – 1961
Chassis/Body Box section chassis with steel body
Wheelbase 102-inches/2,591-mm
Length 177-inches/4,496-mm
Width 64½-inches/1,638-mm
Front Track 51¼-inches/1,302-mm
Rear Track 51¼-inches/1,302-mm
Weight Fixed-Head 3,220-pounds/1,460-kg
Drophead 3,220-pounds/1,460-kg
Roadster 3,158-pounds/1,433-kg
Suspension (F) Independent By Torsion bars,
double wishbones, telescopic shocks and anti-roll bars.
(R) Live axle, semi-elliptic springs and telescopic shocks
Engine Cast Iron straight-six with alloy
cylinder head
Displacement 3,442-cc
Bore x Stroke 83 x 106-mm
Compression Ratio 8.0:1
Induction Twin SU 1¾-inch SU carburetors
Power 190-bhp @ 5,500rpm
Transmission 4-speed manual with synchro on
2, 3 and 4, with optional overdrive or with optional automatic
Brakes Discs on all four wheels
PERFORMANCE
Top Speed: 123 mph
0-60mph: 8.5 seconds
Av. Fuel consumption:
20.5 mpg (imp)
VALUATION
Price at Launch $4,643
Excellent $78,300
Good $61,500
Average $38,500
Poor $22,000
