BMW’s new M5 has been spied in winter testing in Sweden.
The new performance saloon, known internally under the codename F10M and due to make its first public appearance at the Frankfurt motor show in 2011, is set to mark a major departure from its predecessors by adopting turbocharging for the first time.
The decision is part of the drive to cut fuel consumption, a key element of BMW’s Efficient Dynamics programme. M division’s head of development, Albert Biermann, said the new driveline will also receive taller gearing, helping to cut CO2 emissions by 20 per cent, from 344g/km to around 275g/km.
“We’ve been forced to switch to an engine offering greater low-end torque than the naturally aspirated engine to ensure it can cope with the longer axle ratio,” Biermann said. “It’s the only real way we can balance achieving the environmental improvements we want while retaining similar levels of performance to today’s car.”
The engine’s output remains secret. But with the same unit pumping out 555bhp in the X5 and X6 M, the new car should stick to the M5 tradition of being more powerful than the car it replaces.
The most noticeable difference will be the way the new engine delivers its power. The V10’s 500bhp comes at 7750rpm, but the V8’s peak power should arrive at not much more than 6000rpm.
More than outright power, though, it is the added torque that is likely to bring the biggest change in character. Biermann indicated there will be a 30 per cent increase, taking torque from today’s 383lb ft at 6100rpm to somewhere around 500lb ft at little more than 1500rpm. Biermann is also confident the V8’s unique induction system will provide similar levels of throttle response to today’s model.
The early prototype pictured here is one of 10 road-going mules for the new M5. It is being used to test the cooling provided by a new front end. “The development process is at an early stage. We’re concentrating on the durability and cooling of the driveline at the moment,” said Biermann.
The V8 means the M5 will require additional cooling capacity for the intercooler as well as a means of extracting hot air created by the turbochargers.
Along with the new engine, the car will also get a new gearbox, a beefed-up version of the M3’s seven-speed DCT (dual-clutch transmission), as previewed on the 25th anniversary version of the M5 unveiled last week.
Although BMW has just introduced a new petrol-electric hybrid system on its new Active Hybrid 7, it has not been considered for the M5 due to the 100kg it adds to the car’s weight.
Weight saving is playing a big part in the M5’s development, with carbonfibre being used in the bodyshell. BMW is working on a carbonfibre roof and bootlid, mainly because, being sited on top of the car, they are less vulnerable to impact damage.