Modern automatic transmission technology meets Jaguar XJ-S unleashed

You can send the hate mail to the usual address, but I’ll come right out with it and admit that despite being an XJ-S fan I’ve often found the V12 cars rather underwhelming in standard form. The late 6.0-litre is a formidable beast but given its complexity and additional capacity I’ve frequently found myself wondering if the 5.3-litre offers a great leap over the late six-cylinder cars.

Until now, that is. As something of a wildcard, Motor Legends had brought along their own XJ-S convertible to the photo shoot alongside the two E-types and naturally, it also featured the six-speed Ford box.

This is in fact the easiest conversion of all three, the bodyshell accommodating the new gearbox without alteration and the installation requiring little more than a modified crossmember.

It’s also the most convincing demonstration of the huge progress in transmission technology over the years. Whereas the 4-litre cars used a four-speed ZF box, the 5.3-litre V12s employed a three-speed General Motors box chosen primarily to handle the torque and it’s not until you sample a car with a more modern unit that you realise just how limited it is.

On the same test route as the E-type, the XJS feels so much more alive than it does in standard form, with a character which is so much more eager than the gently wafting demeanour it has with the GM box. Like the E-type conversion, the box is set up to lock up in the higher gears on a gentle throttle and there’s a similar reduction in engine revs in top gear which corresponds to a 30% improvement in fuel economy which in mixed A-road and motorway use jumps from 17mpg to 24mpg – or in other words, an extra 100 miles range from a tank.

Away from the motorway though, the V12’s ample heft is just an ankle flex away and the seamless changes of the Ford box complement the V12’s smooth power delivery beautifully. This really is the V12 XJ-S as it could have been and its engaging character is more lively than even the late 6.0-litre cars with their four-speed GM box.

Having driven this car regularly before and after the conversion, Andrew reckons the six-speed conversion feels like an addition of something in the order of 100bhp over the standard car and having sampled it for myself, I’m inclined to agree.