New BMW M5 revealed with 592bhp and four-wheel drive

However, despite these increases and the adoption of four-wheel drive, BMW M has managed to reduce the kerb weight by 25kg over the fifth-generation model, at 1855kg. Weight-saving initiatives employed on the new M5 include an aluminium bonnet, carbonfibre roof, a boot-mounted lithium ion battery and what is described as “a lightweight exhaust system”.

One of the keys to the M5’s enduring success through the years has been its practical four-door layout and comparatively roomy interior. The new model continues this by offering seating for up to five people and a nominal 530 litres of luggage capacity. Inside, there is a new multi-function steering wheel, M-specific digital instruments and electrically adjustable seats.

In pictures: Autocar's history of the BMW M5

Mounted longitudinally up front, the engine used by the new M5 is a development of its forebear’s twin-turbo 4.4-litre V8. The direct-injection petrol unit receives new turbos, a revised intercooler, increased fuel-injection pressure of 350 bar and a new high-capacity oil pump.

Power is increased by 40bhp over the standard version of the previous M5, at 592bhp, and it is delivered some 400rpm lower than before at 5600rpm. This endows the new model with a powerto-weight ratio of 319bhp per tonne, which is 24bhp per tonne more than its predecessor. Torque is also up, by 51lb ft. A stout 553lb ft is developed over a wide, 3800rpm range between 1800rpm and 5600rpm. Additionally, the driver can choose between three modes — Efficient, Sport and Sport Plus — via a Drive Performance button.

The increased engine performance allows the new M5 to match the output of the 30th anniversary M5 launched in 2014, albeit with an added 37lb ft. To put this into perspective, the Mercedes-AMG E63 S 4Matic’s twin-turbo 4.0-litre V8 powerplant kicks out 603bhp and the same 553lb ft, and the Audi RS6 Plus’s twin-turbo 4.0-litre V8 engine delivers 597bhp and 516lb ft.

Although BMW is talking up the fuel economy of the M5’s revised engine, its combined cycle average of 26.9mpg and CO2 rating of 241g/km fail to better the claimed 28.5mpg and 232g/km of the old model.

The intensity of the exhaust note is controlled by a flap within the exhaust system and influenced by the different driving modes. An M Sound Control button allows the driver to reduce noise levels when desired.

The M5’s boosted reserves are channelled through a new eight-speed torque-converter automatic gearbox with remote steering-wheel-mounted shift paddles. A so-called Drivelogic software package provides it with three different driving modes as well as a full-manual mode for sequential shifting via a rocker switch located on the centre console. The ZF-engineered unit, which is combined with a 3.15:1 final drive ratio, replaces the Getrag-produced seven-speed dual-clutch unit used by the fifth-generation M5.

An even more significant departure for the M5, though, is the adoption of four-wheel drive — a first for the M5. Dubbed M xDrive, the hardware of the four-wheel-drive system is based around that used in standard 5 Series xDrive models and BMW M’s existing Active M differential. However, a sophisticated software system with proprietary code developed in-house by BMW M is claimed to ensure drive is sent to the front wheels only when the rear wheels are unable to transmit any more power to the road and additional traction is required.

The inclusion of M xDrive has allowed BMW M to offer a variety of different driving modes, the most aggressive of which, M Dynamic, permits pure rear-wheel drive in a process designed for track use.

BMW M’s decision to eschew traditional rear-wheel drive for the new M5 comes just over a year after Mercedes-AMG announced that the E63 would be offered exclusively with its own 4Matic four-wheel drive set-up. It also brings the M5 into line with the RS6, which has featured quattro four-wheel drive since its inception in 2002.

The added traction delivered by the new M xDrive four-wheel-drive system is reflected in the M5’s official 0-62mph time, which betters that of its rear-wheel-drive predecessor by a full 1.0sec, at just 3.4sec. This is the same time quoted by Mercedes-AMG for the E63 S 4Matic and beats the RS6 by 0.5sec. BMW M also claims a 0-124mph time of 11.1sec.

The nominal top speed of the new M5 is pegged at 155mph, although customers can have that raised to 190mph by specifying an option called the Driver’s Package.

The increase in straight-line performance helps to distance the new M5 from the recently introduced M550i xDrive, whose 456bhp version of BMW’s turbocharged 4.4-litre V8 engine propels it to 62mph from rest in 4.0sec and to a top speed of 155mph.