Automotive History Tidbit: The Automatic Version of the Jaguar Mk X 3.8 L Was Just As Fast As the Manual Version and Got Better Mileage

Sometimes it’s good to bust popular assumptions, like the one where all older cars saddled with primitive two and three-speed automatics were always and inherently slower to accelerate, had a lower top speed, and got worse fuel mileage than their manual transmission counterparts. In the process of looking up something, I stumbled into some recaps of the first two UK magazine tests of the new 1962 Mark X, which came only with the 3.8 L XK engine, the 265 hp triple carb version as used in the XK-E. One tested an automatic, the other a manual. The results are not what I or you would have likely expected.


Autocar magazine did not manage to get its hands on a MkX until November 1962 when they tested 8172 RW, an automatic. Top speed was 119.5mph, the 0-60mph time was 10.8 seconds and fuel consumption was 14.1mpg.

8172 RW had 13000 miles on the clock and Autocar paid it several compliments: ‘There was not a body creak or rattle… almost sports car stability through fast bends and over rough surfaces……..The aroma of good leather pervades the interior, and this with an abundance of timber veneer gives it almost the cosily affluent air of Edwardian library’.

A year passed before the rival Motor magazine tested a manual overdrive MkX, 1196KV. With 1196KV, the men from Motor attained a top speed of 120mph and a 0-60mph time of 10.8 seconds. Overall fuel economy was 13.6mpg.

Ok, one could argue that a certain degree of deviation was inherent in any two engines from the assembly line. But the fact that the automatic had exactly the same 0-60 time and top speed, and got slightly better mileage suggests that there just wasn’t any inherent difference between the two. I should point out that the 3.8 L Mk X did use the rather advanced BW DG automatic, which operated in direct mechanical drive in top gear, bypassing the torque converter. And as I’ve often pointed out, a three-speed torque-converter automatic has every bit as wide an effective gear ratio spread as a four speed manual. And the Moss manual in the Jaguar was not exactly the quickest-shifting unit in the world. Chrysler proved with its Torqueflite automatic that its cars could be as fast or faster than a four-speed on the drag strip, except in the hands of the very best shifters.

Motor goes on to say this about the Mark X:

‘If the car cost another £1000 (it then cost £2082), as it reasonably might, no doubt the sound damping and trim would be much better. Although generally quiet, the engine and gearbox can be clearly heard under heavy acceleration and the decorative woodwork has a skin deep quality, revealed by close inspection. Like the gracefully bulbous sides that make for thick doors rather than interior space, effect has been placed before function: some people like it, others do not. An absurd lack of lateral support mars the otherwise comfortable seats in which five people may stretch and relax, and there is vast luggage space in the boot. Heating and ventilation fall short of many cars costing a third as much. The excellence of the handling, brakes and steering all masked under certain conditions by various shortcomings, and the manual gearbox, although mastery of it can give great satisfaction, is elderly in design and, to most drivers, out of place in such plush surroundings. The automatic alternative is a more natural choice.’

This apparent critique of a Jaguar incurred the wrath of the Coventry concern and the editor of Motor ended up writing an apology to the company.

Ah yes, mustn’t criticize the cars of the home country too much now, eh?