Across Portugal in the new Jaguar XE

Jag's engineers talk about "50-metre feel". It's a refreshing admission that five years' effort and £1bn investment can be undone in a heartbeat if the basics aren't right.

Top Gear's version is called the "5am start". To be brutally honest, I'm not a big fan, but you know the score: there are cars you'd happily set the alarm for, usually the ones that dribble with horsepower and make a sound like Brian Blessed gargling Madras-infused mouthwash.

The Jaguar XE is not one of those. It's much more important than that. So important that thousands of jobs have been created in the Midlands to build it, and that its success or otherwise will have a genuinely seismic impact on the brand's bottom line. Whiskery members of the automotive media have written that sentence a lot down the years. This time it's For Real.

Pictures: Richard Pardon

This feature originally appeared in the February 2015 issue of Top Gear Magazine

So it's a good job that the XE passes the test that precedes even the 50-metre feel, the one that connects your eyeballs to your heart. I've seen it at previews, and blinking like a newborn under scalding motor-show lights, but wreathed in mist outside a hotel on a chilly Portuguese morning is another matter. Not even the presence of ‘prototype' stickers on the doors distracts the critical eye, although there are shades of bubble-wrap Citroen Cactus about their effect. (Full declaration: our car is apparently 94 per cent finished, the six that aren't contained in some uneven interior trim and a satnav that's due some software upgrades.)

It helps that TG's test car is the 3.0 S, the 335bhp supercharged range-topper that wears fatter Dunlops, 19in alloys and less chrome finery. But nailing all of the now-familiar Jaguar design tropes is far trickier on a compact saloon aimed at the mass market than it is on image-building eye candy such as the F-Type.

There's no point me wibbling on about it here because, although design is now accepted as the key differentiator in the car business, it's also the area where the only opinion that matters is yours. You either like something or you don't. Two observations, though: Jaguar's command of sharp radii and the flow of the lines on the XE's bonnet mark the front of this car out as something special. And the rear end is arguably even better resolved - purposeful, stubby, strong graphics, all that cool stuff.

In fact, now is probably a good time to introduce the XE's twin nemeses, the BMW 3-Series and Mercedes Benz C-Class. We'll be hearing from them again in different contexts (and in Ollie's test, which follows on page 89), but the 3 looks oddly over-evolved these days, and there's something about the C that's admirable rather than desirable.

There are two big engineering stories on the XE, and both feed into this 50-metre-feel metric. The most important is that Jaguar has poured gazillions into refining the aluminium processes it's been exploring since 2003's XJ. The XE's body is more than 75 per cent aluminium, with all the benefits that flow from that - it weighs less while delivering extra stiffness and rigidity. This goodness is mostly manifest in the monocoque, but aluminium is also used in the A-pillars and the front and rear crash structures. The B-pillars use aluminium reinforced with high-tensile steel, separated by a layer of high-density foam. It's all riveted and glued together rather than welded, adding an unimpeachable USP in this everyman market sector.

Fifty metres is probably too short a distance to know for sure, but the XE immediately feels like a high-quality object. It's almost in the ether; it's certainly evident in how the doors feel when you pull them shut (and they're made of steel). The XE is aimed at big company-fleet nabobs and increasingly spoilt company-car user-choosers. Its three-year RVs are best-in-class, and all the numbers have been crunched with empirical precision to keep the bean-counters happy. But you'll appreciate the door thunk on a wet Monday morning in Milton Keynes.

You'll also like the high level of perceived quality inside. The cabin layout is simple and strong; the materials, a tactile and practical mix of soft leather and durable-feeling plastics. There are proper dials rather than a TFT display, and the all-new eight-inch InControl telematics system is simple and intuitive, if not particularly nice to look at. Needless to say, it'll talk to your Apple or Android device, and an app can pre-heat the cabin a week in advance and warn your dealer if something's amiss with the car. Back in the real world, the steering wheel feels absolutely lovely.

Then there's what it's connected to - the other significant engineering story. Jaguar's chassis guru, the inestimable Mike Cross, is a stickler for steering feel, a man who probably assesses the way his corn flakes leave his breakfast bowl for linearity. Mike prefers hydraulic assistance, but the XE is the first Jaguar to use electric power steering. Why? Because efficiency outpoints interactivity on the box-ticking front, and EPAS cuts the 3.0 S model's CO2 emissions by three per cent. Jaguar insists the control software is now so good the system can even compensate for changes in ambient temperature. The rest is subjective.

It feels largely spot-on to me, as we head north from our base near Estoril - the circuit on which Ayrton Senna scored his maiden F1 victory in 1985 - bound for the Serra da Estrela national park, well over 200 miles away near the town of Covilha, but home to some great roads and scenery. We have one day only to immerse ourselves in XE, hence the early start and typically TG ambitious plan. No quick bimble round the block for us.

The range starts at £26,995 for the base 2.0-litre petrol, with our 3.0 S the priciest at £44,870, until a fiery R version turns up down the track. Jaguar calls the paint scheme Italian Racing Red, a knowing counterpoint to British Racing Green and another sly nod to the fact that character is the commodity that separates its efforts from those of the German übermensch. We have a long motorway schlep ahead of us, the domain the XE is destined for.

It's immediately deeply satisfying. Elsewhere in the range, the XE gets new Ingenium engines, but the S uses the supercharged 3.0-litre V6 from the F-Type. At cruising speeds, the overall picture painted by the XE is as accomplished and refined as cars from the class above, maybe even the one above that. Subjectively, it feels like a small XJ. As surely as the winter sun dissipates the mist, the XE casually smothers the motorway miles.

In addition to its largely aluminium structure, the XE uses a trick suspension set-up, with double wishbones at both ends and a clever multi-link rear with forged toe links, control arms and hollow castings. EU money hasn't blessed Portugal with the same network of billiard-table-smooth motorway surfaces as its Spanish neighbour, but the XE S rides this choppy patchwork with palpable finesse. It has adaptive damping, whose parameters are fixed. Personally, I'd trust Jaguar of all people to identify the optimum setting, and don't feel the need to flick between the usual Comfort, Sport and Please See Your Osteopath settings.

It's not a home run, though. Out of Covilha and into the national park, the climb up begins with a looping ribbon of second- and third-gear hairpins, before opening out into faster fourth-gear sequences. This is where a car like BMW's 335i M Sport excels (at £38,260, it's also cheaper, at least until the usual options-list burglary begins). I reckon the XE has the sweeter steering (just), but its engine feels oddly tight, and the ZF eight-speed auto - identical to the one used by BMW - isn't the paragon of smooth quick-wittedness I remember. It's most likely an ECU calibration thing, but it still jars. There's no diff, either, so while you can pile into a tight corner with fantastic abandon, you'll exit messily with the inside rear wheel spinning. Lesser XEs might be less prone to this exhibitionism, and it's only a problem if you insist on driving like your hair's on fire.

I didn't realise Portugal had ski resorts, but we find them. There are also religious statues carved into the rock face, and mad-looking buildings and dams. It's all turned very Where Eagles Dare. The XE's traction control has been beefed up to include All Surface Progress Control (ASPC), a cousin of Land Rover's all-terrain control, whose software does sophisticated battle with snow and ice. It works, but we could use winter tyres this far up; there's black ice about. We don't mess about here for long.

The XE pours itself back down the mountain like well-engineered treacle. It generally brakes, steers and handles like you hoped it would, perhaps even better. Having fully established its NVH credentials, we let the Meridian sound system do its most excellent thing.

No question, this car has an immensely tough task ahead of it, trying to crowbar open a market segment that's beset on all sides with challenges - in the form of unapologetic business orthodoxies, BIK, and two of the finest real-world technology products of all, outside even the confines of the car industry.

The 3-Series remains the superior driving machine, by a margin most wafers would struggle to measure. The latest C-Class is a sublime place from which to ply Europe's motorways. But the BMW can feel a little edgy, and in swapping its sports saloon ambitions for absolute comfort, the Mercedes suddenly feels very grown-up. Could the Jaguar XE have found the sweet spot between the two? For 50 metres and beyond, we reckon so.