Audi will launch a muscular new RS6 Avant in the UK next July, after its premiere at the Geneva motor show. The estate boasts a 190mph top speed, a 0-62mph time of 3.9sec and a 28mpg official combined economy figure.

Developed and built by Audi’s independent Quattro GmbH division, the all-wheel-drive, estate-only RS6 is powered by the twin-turbo 4.0-litre V8 that is already used in the S6, S7 and S8.

In the new RS6, however, it develops 552bhp between 5700rpm and 6700rpm, and a constant 516lb ft of torque from 1750rpm to 5500rpm.

The power output is 28bhp down on the 5.0-litre V10 of the previous RS6, but the torque figure increases by 37lb ft.

Two large twin-scroll turbochargers sit in the ‘V’ of the engine alongside the intercooler, a layout chosen to keep turbo lag to a minimum.

As well as stop-start, the V8 uses fuel-saving ‘cylinder on demand’ technology to shut down four of the eight cylinders when the car is developing between 25 and 40 per cent of maximum torque.

In base form, the RS6 is restricted to 155mph. An optional Dynamic Package raises that to 174mph, while the next-level Dynamic Package Plus allows 190mph.

Despite these autobahn-storming top speeds, Audi claims the new RS6 is 30 per cent economical than the previous V10 model, with a CO2 figure correspondingly lower at 229g/km.

The V8 is mated to a ZF eight-speed automatic transmission, equipped with shorter, closer, lower ratios and a longer-striding top gear. Paddle shifters are standard.

The quattro drivetrain also gets a tweaked self-locking differential with its own oil cooler. A Sport differential — which can continuously distribute torque between the rear wheels — will be an option.

The RS6’s air suspension rides 20mm lower than the S6 and is combined with continuously adaptive damping. There will also be an optional Sports Suspension Plus DRC set-up, which combines steel springs and Dynamic Ride Control and diagonally interconnects the three-setting dampers.

Also new are lighter brakes with 390mm front discs clamped by six-piston calipers, while 420mm carbon-ceramic discs are available as an option. Standard wheels are 20-inch forged alloys, with  21-inch rims optional.

The new RS6 is around 100kg lighter than the previous model, in part thanks to aluminium body panels and the new MLB platform’s part-aluminium front structure.

In addition, the V8 engine is just 500mm long, which improves weight distribution compared with the V10 model.

A distinctive feature of the front-end styling is a ‘split’ grille. The grille’s lower portion is dominated by a 3D ‘quattro’ script, which may appear on more Audi models in future.

Like all quattro models, the RS6 is individually developed and has been subjected to 5000 miles of testing at the Nürburgring before being signed off for series production. It is also built on a separate production line at the firm’s Neckarsulm facility.

The quattro division expects to build around 12,000 cars this year. It built a total of 5500 V10-engined RS6s.

UK prices and specs have yet to be finalised, but a base price of around £77,000 looks likely. That will rise significantly, however, when the various dynamic package options are added in.