Facelifts are a bit of a tricky business. On the one hand, they can offer up real cosmetic enhancements; on the other, you end up with Donatella Versace and a legitimate reason to donate your retinas.

For the most part, however, facelifts are an answer to looking a little tired and a little long in the tooth.

So it goes with the updated A-Class; renewed competition from sources as varied as BMW, Volkswagen and even Mini has made a few areas of the pretty little hatch feel older than – and even outshined by – its competitors.

Then, of course, there was Audi's ultimate insult in the RS3, a hot hatch that outstripped even the mighty, AMG-powered A 45 in terms of sheer brawn.

Clearly, Mercedes felt it was high time to get out the scalpel.

From the outset, it's clear the little Merc's surgery isn't purely cosmetic; the real work has gone on behind the scenes, especially towards the top end of the range.

The A 45 now boasts 280 logic-defying kilowatts from its tiny 2.0-litre engine, restoring Mercedes' place as the hyper hatch king – at least in terms of brute force.

But it doesn't stop there for the manic mini-Merc, with a clever locking differential now available for the front axle to improve on its already formidable all-wheel-drive system.

The second-tier – if not second-fiddle – A 250 now comes as standard with the same all-wheel-drive setup as its AMG big brother, minus the option of a race-ready front differential.

The extra weight in the A 250 is offset by a five-kilowatt power bump – bringing the total to an even 160kW – but it's the extra grip and stability that should prove the biggest draw card to the already exceptionally popular model.

A seven-speed dual-clutch automatic is still standard across the range and, unfortunately, there's still no chance that a manual gearbox will ever be more than a pipe dream.

However, since its launch in 2013, Mercedes has smoothed over the rougher aspects of the A-Class's gearbox, offering a more responsive, faster-shifting unit in the updated model.

As well as a mechanical overhaul, the updated A-Class also debuts a range of new tech as standard fitment, such as the introduction of user-selectable driving modes across the range.

Mercedes' so-called 'Dynamic Select' function allows drivers to tailor the engine, gearbox, suspension, steering and even the strength of the air conditioning to suit their driving style and fuel-saving ambitions.

The A 45 gets its own unique AMG-style selector, offering four pre-programmed options that range from AMG's approximation of comfort all the way up to full race mode.

There's also a fifth, do-it-yourself mode, which lets you modify each setting individually, letting you mix and match soft suspension with full-on throttle response, should you choose. And you should.

Mercedes has ensured the A-Class will continue to grace the far end of a waiting list, well into the future

Inside the cabin, previously optional tech like satnav, blind spot detection and keyless ignition are now standard across the range, as is a reversing camera.

The excellent COMAND system with the Harman/Kardon stereo is a pricey, $3000 option on all but the A 45, but offers a raft of media connectivity and a large, iPad-style display to warrant its asking price.

There are a few subtle cosmetic tweaks to the front and rear bumpers, but Mercedes has had the good sense to leave well enough alone, relying instead on mechanical and technological improvements.

The A-Class's fundamental weaknesses are unchanged, of course – the gorgeous sloping roofline translates to a tight back seat, for instance – but its previous shortcomings have done little to stem Australia's voracious demand so far.

And, with a few well-placed nips and tucks, Mercedes has ensured the A-Class will continue to grace the far end of a waiting list, well into the future.