Good: simply stunning levels of quality and comfort, refinement, decent performance and economy, improved ride

Not so good: still not a barrel of laughs to drive, subtle styling inside and out, punishing option prices

So, what do you want? Glamour or staying power? If it's glamour you're after, there are certainly others out there. There's the endlessly enjoyable BMW 3 Series, lurking just within the peripheral vision of every sports saloon buyer. There's the really gorgeous Jaguar XE, which looks wonderfully taut and sleek. And there's the Mercedes-Benz C-Class, which somehow seems to be both agedly patrician and yet youthfully sporty at the same time. In an aesthetic sense then, the rather under-stated Audi A4 rather has its work cut out. Audi's decision to make the styling of its new mid-size sports saloon far more a quiet evolution than something, you know, more exciting, is entirely in keeping with the hone-it-carefully etiquette of modern German car engineering, but in an era of diminishing attention spans, and with the new Alfa Romeo Giulia just around the corner (which exerts some of the same effect on eyeballs as Scarlett Johansson slipping into something clingy and silky), I'm not so sure how this is going to play out.

Then again, the A4 has never been the extrovert of the Audi family. Leave that kind of thing to the TT and the A7 Sportback. The A4 has, since the original model was first launched, been much more about quiet, understated appeal and I think we can agree that that box has been thoroughly ticked. It may look an awful lot like the old one, but then that was a handsome, crisp-looking car so perhaps that's no bad thing.

There is much the same story on the inside. You can have a much ritzier cabin for your A4 than our 2.0-litre TDI 150hp S line test car came with. In spite of an options-inclusive €55k price tag, it lacked the full-width 'Virtual Cockpit' digital instrument pack, it lacked fancy seats and exciting seat colours or trim options. In fact, it all looked a bit dour in regulation Germanic black and aluminium, in spite of the car's massive price tag.

But of course, this is not about being a show pony. This is about the staying power part of the equation, and here is where the A4 starts to stun its playing partners by quietly turning over trump card after trump card. The seats may not look exciting, and the optional suede-like finish on our car's pews will prove a crumb-magnet nightmare for anyone carrying kids on a regular basis, but boy are they comfortable and supportive. Mile after mile, hour after hour, it matters not - these are great seats.

And those might not be the whizz-bang digital instruments, but they're clear and classy and damn near perfect to use. And that central infotainment screen may not be a touch screen (even though it looks it) and it isn't the gorgeously slim, foldaway one from the Audi A3, but it's bright and clear and logical to use (once you've fruitlessly stabbed it with your finger a couple of dozen times before remembering it's not a touch screen) with the MMI system click wheel down to your left. And it has Apple CarPlay, which is not the panacea to connectivity ills that it might be, but is certainly handy and requires less brain effort than most car makers' built-in systems.

The whole A4 is around 120kg lighter than it used to be (in spite of which it retains good rear seat space and a healthy 480-litre boot) so there is some efficiency to be mined, here. The official 70mpg will certainly be beyond the ability of most drivers in normal conditions, but a bit of care on a longer journey should see the sunny side of 65mpg, and even around town it refuses to budge much below 50mpg in most circumstances.

Better still, the 2.0 TDI engine has been to a better finishing school than most of its rivals. Rather than clattering and blaring, it just seems to exude a gentle, deep thrum unless you're actually revving it to death, so it's much more refined and quiet than the rival engines from BMW, Jaguar and Mercedes-Benz.

It also manages to punch above its weight a little in performance terms. Figures of 150hp and 320Nm don't sound like much and aren't, but that Weight Watchers regime has paid dividends - the A4 never feels anything less than pleasingly swift in this form, and while a six-speed manual gearbox may not quite be the done thing in this class these days, it snicks neatly between ratios, so after a while you don't much miss the optional auto.

The driving experience remains a touch flat though. The steering is weighted to near perfection, and is almost totally free from friction or unwanted vibration. The suspension is far more subtle and supple than was previously the case, and even on the optional 19-inch rims and S line sports springs (previously just a long-winded way of saying you enjoy visits to your local osteopath) the ride is firm, but nicely judged and carefully damped, not hard nor harsh.

And yet it's a very hard car about which to feel enthusiastic when driving. You tell it what to do and where to go, and it faithfully and securely does so, but there's little or no sense of engagement or enjoyment. It's all a bit too detached. The BMW, Jag and Merc may not be as well-made nor as refined nor as economical, but they all offer far more encouragement to the keen driver.

While this A4 is the very Acme of safely-same-again styling, the engineers have obviously had a deeper pot of overtime into which to dip. The whole thing just feels so beautifully assembled, so finely wrought, that you start to forgive the lack of fireworks and dancing girls. The rivals may be able to put up a more exciting, more enticing initial performance, but I reckon the A4 has that elusive staying power. I'd suggest that after a week with the A4, you'd be a touch bored with it. After a month, your attraction will have grown and a year or more would likely see the keys having to be pried from your palms by force. Staying power is an illusory, ephemeral quality, but I think the A4 has it by the bucket-load.