Medium cars have overtaken large car sales in Australia and the Opel Insignia, the new mid-sizer from General Motors’ German brand, is hoping to grab a slice of the action.

The Insignia represents the flagship of Opel’s range that goes on sale from September, sitting above the Corsa city car and Astra small car.

The Opel Insignia even fills a hole for GM in the medium-car segment while Holden waits another few months for its new Malibu to replace the floundering Holden Epica.

As with the Opel Corsa and Opel Astra, the Insignia’s predecessor has history in Australia as a rebadged Holden – though it was then known as the Vectra.

Visually, the Insignia should be more memorable with its more interesting shape – whether in the sedan or wagon forms being offered locally.

Jump into the driver’s seat and the Insignia further distances itself from the Vectra. There’s a far more premium look and feel to the cabin.

One particularly notable interior design element is how the door trim arcs almost seamlessly into the dash in a way that are reminiscent of the Jaguar XJ and Audi A7 cabins.

The symmetrical centre stack also has a prestige feel and the impression isn’t let down when you push the buttons or rotate the dials. And there’s an almost Volkswagen-like blend of smooth surfaces and soft plastics throughout the cabin.

Opel has decided to pitch its Insignia at the upper end of the mainstream medium car category, so there’s also a grouping of standard features that reflect pricing that starts at $38,990.

Even that entry point delivers leather upholstery with heated front seats, dual-zone climate control and humidity sensor, leather steering wheel and 17-inch alloy wheels.

We tested the higher trim level called Select, which begins at $45,490 and slots bigger 19-inch alloys onto the wheel hubs, brings a sportier-looking steering wheel and pedal set, adds ventilation to the front seats, puts the driver in a seat certified by German ergonomics experts, spruces up the dash with a colour sat-nav system, and illuminates the road ahead with a larger array of lighting set-ups including LED daytime running lights and bi-xenon headlights that can peer around corners.

The front seats of the Opel Insignia Select are excellent, too – blending comfort and support.

Behind those is a rear bench with sculpted outer pews that show Opel is honest about the comfort the middle rear seat will provide adults.

Most passengers should be content with rear legroom, though taller occupants will find rear headroom is compromised by the Insignia’s sloped-roof design.

A day-long Opel launch program that involved speed-dating with its various models meant we didn’t get to spend as much time in the Insignia as we’d have liked, but a couple of hours was enough to sense the company has reached a new level of refinement.

The Insignia proved to be a pleasantly quiet cruiser on the country roads and freeways in NSW’s Hunter Valley region, complemented by a 162kW/350Nm 2.0-litre turbocharged four-cylinder that provides smooth and punchy progress.

It’s no slow-coach off the line, either, with a quoted 0-100km/h of 7.8 seconds, or 8.1 if you opted for the more practical wagon, or 9.6/10.1sec if your choice is the more efficient 2.0-litre turbo diesel variant that uses an official 5.7 litres per 100km versus the petrol’s 8.8L/100km.

Apart from some mild lag if asking for more than light throttle, the petrol engine’s turbocharger is almost omnipresent – in a positive or negative way depending on the buyer.

There’s a noticeable whistle as the turbo spools up before an equally subtle-free whoosh is heard as the wastegate dispels the exhaust gases.

The six-speed auto seems smart enough at picking gears, though paddleshift levers behind the steering wheel wouldn’t go amiss for this particular engine (the gearlever has a tipshift manual mode, though).

There were too few opportunities for us to assess the Insignia’s dynamic qualities, but can report the steering is good for its weighting but not so good for its feedback.

The suspension also seemed quite fussy even at speed, though its ability to cushion occupants from big holes and bumps was impressive.

We didn’t get to test the wagon, but can tell you that, while it shares its wheelbase with the sedan, the body uses its extra 78mm of length to create space for items 1.9 metres long with a total cargo capacity of 1530 litres when the rear seats are folded.

Unusually, though, boot space is identical to the sedan’s: 500 litres. The sedan’s boot is usefully wide and long, and there are split-fold rear seats though there’s only a space-saver spare wheel.

Treat the star ratings we’ve given the Insignia as provisional only based on our early first impressions. We’re certainly intrigued enough by this Opel to give it a more thorough CarAdvice test at the earliest opportunity.