THERE seems to be a perceived wisdom within car design circles that, if it ‘aint broke, don’t try and fix it. Look at the Porsche 911, for example. Its looks have changed very little in the 50-odd years it’s been evolving. And why should they? It was beautiful on day one and it’s still beautiful today.

Last week I tested the new Fiat 500 and that’s barely changed in appearance but, again, why bother? Its cute, retro looks still cut a dash and it’s still extremely popular.

And that brings me onto this week’s test car, the Jaguar XF. Here’s another popular car that’s barely changed. In fact, it’s one of those new models which has to be parked alongside its predecessor to really pick out the differences. But while they might be subtle, they’re certainly there. And I’m pleased to report they’re all for the better, too.

In fact, if you really must wander round with a clipboard to try and pick out all the changes in this version you’d be better parking it next to its younger, smaller sibling, the XE. Because that’s where many of its design elements seem to be plucked from.

Look, for example, at the shorter front overhang; the stylish LED front lights and the rear lights that hint at the style of the glorious F-Type sports car.

1086486_XF_R-SPORT_RHD_005Look a little harder and you’ll notice it’s slightly shorter than it was before, and it sits a little lower. As a matter of fact, it’s quite a bit prettier than the old XF. Not that the old XF was an ugly duckling but, proportionately, this newcomer is just lovely.

The story’s the same inside, too. The old XF’s interior had its good points, but it was starting to look a bit dated. Jaguar’s done a wonderful job of freshening it with the swooshy dash and plush materials of its current line-up, but with a few of the favourite details remaining. Fans of the elegantly rising nob-o-matic gear shifter will be thrilled to hear it’s still included. I know I am.

And despite it being a little shorter, there seems to be more room. Nothing is lost from the interior and that’s an ingenious bit of packaging.

Another trait it inherits from the fabulous XE is its impeccable road manners. It rides very well, but it still feels sporty and “Jaguarish”; more so than the hot versions of the predecessor, in fact.

The current touch-screen infotainment system is an evolution of the Jaguar setup, if not a revolution. It’s fairly easy to get the grasp of, but not quite as intuitive as BMW’s i-Drive system, for instance.

1086487_XF_R-Sport_RhodiumSilver_065The range of engines on offer doesn’t take as much effort to get your head round, though. Petrol models come with a 3.0 supercharged V6 while the diesels borrow from Land Rover to supply another 3.0V6 or two versions of a 2.0 diesel engine – one with 151bhp and another with 178bhp.

The petrol engine is a hoot, obviously, but it’s the diesels that will attract the most buyers over here. And they’re both excellent. They marry up well with the eight-speed automatic gearbox, too.

Pick the bottom-of-the-heap XF with the 161bhp engine, link it to a six-speed manual gearbox and you’ll be chucking out just 104g/km of CO2 and returning 70.6mpg. So it’s reasonably tax-friendly.

Jaguar doesn’t need this car to be this good. It’s long been the darling of the well-to-do middle-management set and rightly so. But It’s never been fully on a par with the BMWs and Mercedes of this world. Until now, that is.

All the favourite Jaguar staples are there, along with excellent handling and a fine ride. In fact, it’s just what a Jaguar should be. It strikes a balance between sporty, sublime and desirable.

Alongside the fresh and funky XE, the sublime XJ and the bonkers F-Type, it might seem like the XF has a far less significant place in the Jaguar line-up. But don’t be fooled; it’s still a Jag. It’s still worth serious consideration.