Sector: Lower medium Price: £24,305–£27,105 Fuel: 50.4–68.9mpg CO2: 107-129g/km

The A3 accounts for a fifth of Audi’s global volume, and despite a conservative styling evolution with the third-generation it’s comfortably the best seller in the premium C-segment. Yet despite a 16-year success story, the lack of a saloon version has left a gaping hole in its product offering.

It’s hard to believe in Europe, where even the biggest-selling hatchbacks struggle to find buyers when they grow a boot, but globally this is far from a niche model. Audi has opened a new factory in Hungary just to build the Saloon, and as many as half of Chinese and North American customers are expected to opt for the three-box version. Once the second factory opens in China – just for domestic customers – 30% of global A3 production will be the Saloon. So it’s big news.

But Audi has no illusions that this will transform A3 sales in the UK. The Saloon arrives here in September, predicted for a 10% share of the model’s sales, and the manufacturer is hoping many of those will be conquests from the mainstream D-segment – customers looking to downsize, but trade up to a more desirable badge.

So, in a similar step to the Mercedes-Benz CLA, the A3 Saloon is coming here with a smaller model range. Most markets will get three trim levels, as in the hatch and Sportback, with the S line package on top. British buyers will be offered the mid-spec trim as the Sport, and the S line as its own model, with sales split evenly between them.

But while the CLA is marketed as a four-door coupe Audi has stuck to the traditional three-box saloon shape. It means the A3 feels brighter and roomier in the back than the CLA, despite being shorter overall.

Wider wheel arches and a short boot make the A3 Saloon feel stocky rather than stretched, and bode well for the next Cabrio which will be based on this instead of the hatchback. Rear legroom is identical to the Sportback, while boot space has grown by 60-litres albeit with a narrower opening than a hatchback.

Launch engines include the 148bhp 2.0 TDI which has proved popular in the rest of the range, and this smooth, efficient unit is predicted to find its way into 35% of UK cars. A 184bhp version will follow in December, along with the 1.6 TDI with range-lowest CO2 emissions of 99g/km. Despite the 45bhp drop in power, this is more than adequate for most drivers while easily returning 65mpg on long journeys. The CLA offers no direct alternative, its most efficient engine is the automatic-only 220 CDI at 117g/km.

Petrol versions include the 1.4 and 1.8 TFSI units at launch, the smaller of which features Cylinder on Demand technology, allowing it to run on two cylinders at low loads. It’s a pleasure to use, light and revvy to drive and switches seamlessly into its fuel-saving mode, but despite a diesel-like 109g/km CO2 output it’s also £300 more expensive than the 2.0 TDI which will blunt its appeal.

Tested on the Sports suspension which will be standard fitment on UK cars, with S line and standard setups as no-cost options, even on heavily potholed roads it felt suppler than the CLA without becoming wallowy through corners. It’s only the largest wheels which give it a tendency to thump uncomfortably over lumpy tarmac.

The Saloon may not be a mass-market car for the UK as yet, but the A3 has become a well-rounded hatchback and its best qualities translate neatly into a worthy compact alternative to the A4. However, the CLA’s sleeker styling could tempt image-conscious buyers away from Audi showrooms.

Verdict:

A more conservative-looking effort than the CLA, but the A3 Saloon offers higher fuel economy, better ride quality and a far less claustrophobic rear bench than its closest rival. With the running costs of a C-segment hatchback and a range based on well-equipped trims, it’s worth considering before defaulting to another A4, and a viable downsizing option from the mainstream D-segment too.