2015 Audi RS3 Sportback priced from £39,950 - plus pictures and first ride

The engine returns a combined 34.8mpg, with CO2 emissions of 189g/km.

By comparison, the RS3 Sportback’s key rival, the Mercedes-Benz A45 AMG, produces 355bhp and 332lb ft from its turbocharged 2.0-litre four-cylinder engine.

However, AMG officials have already promised an increased output when a facelifted version of the A45 AMG arrives towards the end of 2015, hinting that the Audi’s reign as the most powerful car in its class may be a short-lived one.

The RS3 Sportback’s heady reserves are channelled through a standard seven-speed S tronic dual-clutch automatic gearbox offering both manual and automatic shifting. Like the engine, it has been upgraded with what Audi describes as “new solutions for filling the clutches with oil and the interplay with the engine” for improved shift times.

With the driveline switched into dynamic mode, the downshifts are performed with an automatic double-clutching effect for added smoothness.

The S tronic gearbox is allied to a modified electro-hydraulic, multi-plate clutch, four-wheel drive system. Now mounted within the rear axle assembly for improved weight distribution, it sheds 1.4kg over the previous system through the elimination of a pressure accumulator. Drive is constantly varied front to rear with between 50-100% going to the rear, depending on the conditions.

An electronically controlled torque-vectoring function also provides controlled braking of individual wheels for a more neutral line during hard cornering.

In a bid to heighten aural qualities, Audi has provided the RS3 Sportback with a two-stage exhaust, with flaps used to control the flow downstream of the muffler.  

With an official kerb weight of 1520kg, the new RS3 Sportback tips the scales at 55kg under its predecessor. Along with the gain in power, this provides it with a 28bhp improvement in its power-to-weight ratio, at 238bhp per tonne.

Audi claims a class leading 0-62mph time of just 4.3sec, beating the old RS3 Sportback and A45 AMG by 0.3sec. Top speed is nominally limited to 155mph, although buyers will be able to specify an option that raises it to 174mph.    

Reining in the car’s enhanced performance is a newly developed brake system. It uses vented 370mm steel discs with sizeable eight-piston calipers up front and 310mm steel discs with single-pot calipers at the rear. In a first for its class, the new RS3 Sportback also comes with the option of 370mm carbon-ceramic front discs.

Underpinning Audi’s most powerful series production hatchback is a heavily reworked version of the third-generation S3’s MacPherson strut front and multi-link rear suspension.

It has been lowered and also gains a number of unique components, including aluminium pivot bearings at the front end. The tracks are also unique to the RS3, increasing by 24mm up front to 1559mm and by 4mm at the rear to 1515mm. The standard five-spoke alloy wheels are 19 inches in diameter and come with 235/35-profile tyres front and rear.   

As an option, buyers can opt for a magnetic ride system which provides adaptive damping. It is controlled by a standard Audi drive select system, which allows the driver to alter the characteristics of the throttle, steering and damping in four modes: Comfort, Automatic, Dynamic and Individual.  

Also available are matt titanium or high-gloss anthracite black 19in alloy wheels with 255/30-profile tyres up front and 235/35-profile tyres at the rear.

Inside, the new RS3 Sportback receives a series of high-quality appointments commensurate with its price tag. Included are leather-upholstered sports seats, a leather and Alcantara-bound flat-bottomed multi-function steering wheel, a leather and aluminium-trimmed gear lever, unique instrument graphics, stainless steel pedals and Alcantara door trim elements.

Buyers can opt for optional RS bucket seats. With integrated side airbags and a carbonfibre shell, they are claimed to be 7kg lighter than the standard sport seats. Further options include an interior design package with red accents on the knee pad, air vents, floor mats and seat belts. UK cars will also get Audi's MMI infotainment system as standard.

A new saloon version of the RS3 will also follow soon after the launch of the hatchback. The new RS3 will take on rivals including the Mercedes A45 AMG and the long-rumoured BMW M2.