PSST, Opel: we reckon the Insignia wagon has a ready-made market just itching for it.

Everybody knows the series formerly known as Vectra is still – first and foremost – German mid-sized mainstream family/fleet car fodder, just like the Ford Mondeo, Volkswagen Passat, and Skoda Superb.

A Kaiser Camry, if you will.

But forget about the Insignia’s oh-so pretty face, and take a long, hard look at the Sports Tourer wagon’s protruding posterior instead.

Imposing and well formed, it features a clamshell tailgate complete with an outer tail-light assembly backed up by auxiliary inner light clusters to keep it street-legal when driving with that massive door open, Audi Q5-style.

Hefty and solid, industrial-strength struts that might be from a 737’s landing gear hold it all up. Memories of the original Saab 900’s unique and beautifully complex slide/tilt bonnet are brought vividly to mind.

Did someone say Saab? Is it too soon to speak of the recently deceased?

Probably. But this single piece of engineering, along with the handsomely crisp and chiselled styling, might just be enough to shift Opel brand perceptions… we don’t know, say 59.3300° North by 18.0700° East…

And take Stock(holm) of this, readers. If we’re talking in the context of this car’s blunt and boxy Vectra predecessor, a model famously unloved by no-one (though the failed Signum version was innovative), the Insignia is one small step for a Euro midsizer but one giant step for GM.

Could it be that the short-lived second-gen Saab 9-5 developed alongside the Insignia during the latter half of the last decade could have resulted in a two-way DNA transfer?

Clearly Opel aimed much higher than it has before, and that’s obvious inside the Insignia as well as out.

OK. We admit it might be pie-in-the-sky stuff. Plus, absolutely no Saab cabin cues exist – no floor-mounted ignition, no fishbowl-effect A-pillars, no ‘Night Panel’ blacked-out instruments.

Indeed, the whole fascia is like ‘an ode to Holden Cruze’ in its presentation – albeit all in a more upmarket fashion.

However, like that tailgate, the doors are satisfyingly weighty, and open wide for easy access, to reveal an interior virtually as spacious as a Commodore’s.

Some fiddling is necessary to find the right driving position, since our top-line Select Sports boasts sumptuous every-which-way adjustable ‘premium’ seats, but the tilting front headrests are a nice neck-cushioning touch.

Cruze-like or not, the vast, swept back dash is immediately logical in its layout, and is aided by an attractive symmetry, big clear buttons, and excellent ventilation.

On the flip side, the centre console area’s stark matte-black surfacing seems scratch-prone and consequently too low-series Commodore Executive for the $50K asking price. We often don’t say this, but more quality bling please, Opel.

The instrument dials appear smart but the multi-function display between them is confusingly choc o’block full of intimidatingly scientific-looking information presented in the sort of ‘90s low-fi red markings Audi abandoned ages ago.

We’re no fans of the tinselly chrome dial surrounds either.

We are also frustrated by the illogical sat-nav controllers set lower down the console lacking a definitive ‘select’ action, it makes data input difficult.

Familiarisation helps here but the whole operation feels unnecessarily complicated – unlike the superb climate control system. At least the screen itself is set up high for all to see.

Like every GM vehicle of late it seems, the attractive three-spoke wheel is packed with remote switches for the cruise control, trip computer, audio sourcing, Bluetooth phone (but no audio streaming), and (impressively accurate) voice control system.

Wagons nowadays are rarely anything less than a posh combination of ‘Sport’, ‘Estate’ and ‘Tourer’, and the Insignia subscribes to that by walking a fine line between style and practicality for passengers and luggage alike.

But the back seat area is let down a little by an abundance of hard, cold, black plastic that would have disgraced a ’99 Hyundai Sonata.

Yet in terms of comfort and pure functionality, the largish Opel doesn’t put a foot wrong.

Wide enough for three-abreast travel, the rear bench has a deep cushion base providing ample support, and even a perched-up centrally located passenger of about 180cm should have sufficient head and leg room.

Along with unencumbered access via large rear doors, all the usual family-friendly accoutrements are featured – including air vents, grab handles, map pockets, cupholders, storage bins, and armrests.

And then, of course, there’s that tailgate.

Despite the oversized struts a surprising amount of muscle is necessary to hoist that heavy lid up, while an electronic soft-close mechanism keeps the whole kit and caboodle from slamming shut.

There is a useful hidden area below a long, wide, and agreeably deep main floor (that extends from 500 litres to 1530L with the split/fold seats dropped), a ski port is fitted, and the cargo cover has one of those neat one-touch tap releases that really ups the premium ante in what is a very practical wagon.

Not surprisingly, then, when you turn the ignition key, the Insignia Sport Tourer continues to be a tale of two cars.

Around town and the suburbs, you are likely to be impressed with the sheer grunt from the 118kW/350Nm 2.0-litre CDTi, but not its gruff, loud nature.

Driving the front wheels via a conventional (yet effectively smooth and well-spaced ratio-wise) six-speed auto, the four-pot turbo-diesel dishes out oodles of torque for tyre-scrubbing off-the-line acceleration with only minimal lag.

Obviously the traction control systems have been calibrated carefully, for there’s not much torque steer, unless the conditions are wet. But it is easy to burn rubber out of every side-road if you’re feeling anti-social.

Stay within the Opel’s torque band, and the sheer force of overtaking performance is quite eye-opening, with drivers needing to be careful not to significantly exceed the speed limit doing so. This CDTi does not hang back.

Yet even during our high-speed performance runs, our fuel consumption didn’t rise above 7.8L/100km, underlining the efficiency of the powertrain.

But we can’t decide what’s worse around town – the lack of sufficient diesel sound deadening, or the dearth of small frequency bump absorption from the gorgeous 19-inch alloys.

Sadly, the Insignia’s suspension set-up lacks the suppleness of a Passat and the pliancy of the Mondeo – though to be fair neither has been tested with such large wheels.

Keen drivers may also wish for greater steering feel, but the Opel’s quite remote helm is beautifully weighted and agreeably sharp anyway, for absolutely safe and precise handling characteristics. The body control, too, is confidence inspiring.

Driving away from the ‘burbs, however, is when the Insignia really comes alive.

Showing off its autobahn breeding, on your average B-road it becomes remarkably responsive and agile, yet with the relaxed demeanour its smart styling suggests.

Maybe it’s a combination of speed-related mechanical/road noise increases, but the diesel din really did die down, even when flooring it for a spot of effortless highway overtaking.

The ride, too, soaks up larger bumps with a no-nonsense attitude that city-restricted owners might only dream about.

But the biggest surprise is just how reactive and alive the steering becomes at speed, awakening from its slumber for fast – perhaps even too quick for the unwary at first – reactions to inputs.

Mid-corner bumps don’t faze the Opel one iota, as it just hunkers down and hangs on, keeping the driver’s chosen line every time like a grand touring wagon should.

Stray onto gravel roads, and progress remains steady and composed, while the stability and traction controls don’t over-intrude, so a keen driver can have the tail out a little (and catch it easily enough again) without too much annoying electronic interference.

Our only dynamic concern occurred during our half-gravel/half-bitumen braking test at 80km/h, where the car did dart a little to the right rather than slow down in a straight line like we expected. Other than that, though, the brakes are superb.

So, what a turnaround for the Insignia Sports Tourer CDTi!

From being a chic urban meh-fest to fast, involving and fun open-road tourer, it has really and quite unexpectedly loomed large for wagon buyers wanting more than just plain old practicality.

We can’t help wonder how much more Swede… err, sweeter the Sports Tourer would be with smaller alloys and the 2.0-litre turbo petrol powerplant. Surely they’d eradicate the twin bogies of diesel gruffness and a hard urban ride in one (while costing less to boot!).

Which brings us back to where Opel ought to position the Insignia.

With so many disenfranchised Saab owners out there, the 9-5 connection paired with the right drivetrain/tyre combo could make the Sports Tourer a viable Volvo estate value alternative.

Think about it, Opel. Drop all that double Deutsch ad talk and instead specify your mid-sizer with lighter seat colours, brighter trim inserts, and downsized powerplants, for that pseudo-Scandinavian appeal.

Frankly, the Insignia is a better drive than any GM-era 900 or 9-3 ever was!

Yet, even as it stands so suavely and sophisticated, watch out, Passat, Mondeo, A4, V60 and i40. The Insignia Sports Tourer’s in town and buyers are better off for it.