THE Audi A3 celebrated its 20th birthday just before last Christmas - two decades that have seen it become the mainstay of the brand and set the benchmark in the premium hatchback market.

During that time many a rival will have undergone four or five major overhauls but it is testimony to Audi's preference for evolution over revolution that the A3 is only on its third generation.

Five-door versions like the one I drove, currently defined by the exciting sounding Sportback moniker, have been around since 1999 and cabriolet and saloon models have joined the fold along the way.

Bumpers, grilles and light clusters are also tweaked regularly to keep the look fresh - but line up all three hatchback iterations side by side and the classy, restrained lines and overall profile remain remarkably similar.

That's not to say that the A3 hasn't developed, it's just that, like many of its stablemates, the significant updates have come beneath the skin.

One such change was the addition to the range, during the latest spruce up last summer, of the new 1.0-litre TFSI petrol engine - the first time a three-cylinder power pack has ever featured in an A3 and very much following the current trend for downsized turbocharged units.

Pushing out a maximum 116ps between 5,000 and 5,500 revs it's a peppy little unit which delivers some sprightly performance - especially when zipping around in urban traffic - but still offers a claimed 60 miles per gallon on average.

The 0-62mph sprint comes up in a snip under 10 seconds and a top speed of 128 miles per hour means you won't get left behind on the motorway.

The lightweight new powerpack, mated to a snappy six-speed manual gearbox in my car, also gives the A3 an agile and nimble feel from behind the wheel, responding quickly to both throttle and steering inputs, while a well-balanced chassis and the dynamic suspension that Sport trim brings keep it flat in corners and settled over less than perfect road surfaces.

It's surprisingly quiet too, with Audi having all but eradicated the usual thrum of a three-cylinder engine, even under sharp acceleration and at motorway speeds, when the characterful note would usually become more of an annoyance.

Inside Audi's approach is also for steady rather than radical change but the one thing you know you'll get is quality and the A3 does not disappoint, with plush, soft touch surfaces all around.

Technological advances are to the fore, though, including a new standard-fit smartphone interface.

Typically of the premium German brand, however, many of these are optional extras - adding almost £7,000 to the £20,850 base price in the case of my car.

Definitely the headline act was the £1,395 advanced technology pack, which includes the impressive Audi ‘virtual cockpit' - available for the first time in the A3 - featuring a high-resolution 12.3-inch screen rather than the traditional instrument binnacle.

The driver is able to switch between classic mode, where the instruments appear as they would in the usual analogue display, or infotainment mode, where the navigation map or details of the radio, audio and phone settings predominate with the rev counter and speedometer appearing as smaller dials.

Such niceties are the icing on the cake, though, and the A3 is very well equipped even without them, my Sport trim car boasting 17-inch alloys, sports front seats, dual zone climate control, cruise control and a five-mode drive select system among other things.