Ladies and gentlemen, meet David G.

He’s not fictional, but a father of two, a regular GoAuto reader, a one-time Alfasud owner and a bona fide petrol head.

David contacted us recently about buying a new car. He drives a 2003 Madza6 Limited manual sedan, and after years of faithful yet fun service, an upgrade is in order.

Obviously the new, third-generation model is a strong contender, certainly more so than its somewhat dull predecessor of 2008.

Kindly, David offered for us to borrow his 165,000km example for comparison purposes when we test the 2013 model soon. That will also be his chance to drive the latest Mazda6. David’s reaction will be interesting.

Until then, here’s what we think after a day behind the wheel of several different variants.

Let’s begin by saying that, when Mazda says “all-new”, it really means it. Practically nothing remains from before. Even the front suspension is different – gone are the double wishbones for a pair of conventional MacPherson struts.

That’s the first of many clues that the Mazda6 is very closely related to the successful CX-5, and will share many architectural elements with future models thanks to modular-engineering.

While they are undoubtedly from the same family tree, it’s funny how different the new Mazda6 looks versus the old one, and how different it feels to drive.

The slinky road presence is undeniable. From three-quarter view, both the coupe-like sedan and swoopy wagon are eye-catching. Even the grille – which hurts like a stick in the eye on the SUV – doesn’t look so gormless here. The slight frumpiness of the old model is history.

More CX-5 influences materialise inside. But while the Mazda6’s extra width lessens that vehicle’s dumpy dashboard appearance, we reckon it’s a missed opportunity for something with real sports sedan character and pizzazz. What suits an SUV seems a little dull here.

Japan really seems to be trailing Korea in this regard – let alone Europe.

Not that the fascia is all a failure. Compared to before, Mazda’s engineers pushed back the windscreen pillars for a wider field of vision, added more soft and smooth surfaces while increasing the solid feel to up the premium appearance, and really paid exceptional attention to how users interface with all the controls.

Nice details abound – from the smooth and attractive steering wheel and crystal clear instrumentation, to a proper handbrake and classy piano black trim on upper models. Too bad the monotones in cars trimmed in black bring the ambiance back down a peg or two.

Whether we’re talking about the longest-ever Mazda6 sedan or its 80mm-shorter-in-wheelbase Euro-focused wagon sibling, nobody is likely to find issues with front seat comfort, space utilisation or the merit of the driving position.

And backseat passengers in every one of the exceptionally well-equipped models can access air vents, grab handles, and armrests. But heads need ducking getting in or out – especially in the coupe-like sedan – due to the sloping roofline. Taller folk may wish for a bit more head clearance when sat down, too.

On the subject of tight-ish apertures, the sedan’s boot opening is quite shallow and the long and wide floor isn’t as deep as you might expect. If cargo is a priority the wagon looks and works just fine. As in previous models, a remote rear-seat folding mechanism is fitted.

At the other end of the new Mazda6 is the all-new SkyActiv drivetrain and chassis technology, and here we feel the newcomer has taken five giant steps forward and then two big ones back.

Step forward one: dynamics. The new model benefits from much more rigidity overall, so the handling is crisper, the roadholding exceptional, the body control tauter, and the ride quality – even on the big 19-inch wheels on the GT and Atenza – sufficiently supple.

Some colleagues complained the latter felt too stiff driving out from Adelaide Airport to the beautiful nearby hills, but we experienced no such discomfort. And we’ve felt much worse in the past on the same roads. On balance, then, we’ll call it progress.

Step forward two: refinement. All that extra bracing, combined with a fanatical exorcism of noise, vibration, and harshness pathways, means the Mazda6 is a quieter car than before. Not hard to do, if you are subjected to the daily drone of the earlier editions, but on bitumen that would have German rubber amplifying every sound inside the car, the Japanese vehicle was pretty muted.

Step forward three: engine efficiency. Aided by an eager and intelligently crafted six-speed automatic as standard, the all-new 2.5-litre SkyActiv G direct-injection petrol four-pot powerplant is a lusty, long-legged unit that doesn’t mind being bounced off the rev limiter.

Mazda has long made fine engines (and decent autos), and this is no exception – though curiously at start-up the ‘G’ can sound a little coarse and diesel-like. We understand that if/when Australia switches to standard 95 RON unleaded petrol, the engineers will be able to free up a further 1000rpm of top-end performance, too.

Meanwhile, the 2.2-litre SkyActiv D diesel is also a treat – relatively quiet, punchy in the mid-range, and not prone to off-boost lag. Both engines offer class-leading fuel economy too – unless you add a Toyota Camry Hybrid into the mix.

And step forward five: choice. You can tootle around on a wad of ultra-refined torque in the softer-sprung 17-inch-wheeled Touring, enjoy phenomenal body control and grip in the luxurious Atenza, or reel in your favourite set of corners at the wheel of the base Sport wagon – perhaps the keen driver’s sweet spot in the whole Mazda6 range.

But it hasn’t quite got the medium segment sown up.

Mazda has de-sensitised the steering right on centre, so that crispness of the past models (particularly the original) is no longer there. Consequently at low speeds, the helm feels too light and too dull for our tastes. That’s a heartbreaking move for all of us who used to revel in the sharpness of the old Mazda6.

We also shed a tear for the deletion of the manual gearbox option, with Mazda Australia opting to go all auto this time.

So let’s shorthand this for both you, the reader, and David.

What Mazda has created is top family car value, and a segment front-runner of formidable virtue. That much is clear. Forget the Honda Accord Euro, Ford Mondeo, Volkswagen Passat and Skoda Superb. The Mazda6 is snapping at the heels of the entry Audi A4s, Lexus IS250s, and Volvo S/V60s of this world.

But we can’t help feel David will be disappointed at how muted the steering’s on-centre feel has become. He won’t be pleased about the lack of manual gearbox choice either. Together, do they spell the end of the Mazda6’s true sports family sedan phase?

For most other midsized buyers, however, they’ve never had it so good.