BMW says performance has peaked

Don't expect 0-100km/h times to keep tumbling. We are almost at 'peak acceleration', according to senior BMW M engineer Maximillian Ahme.

Speaking at the 2013 BMW M Track day at the Sepang F1 circuit in Malaysia this week, Mr Ahme told Drive that huge standing-start acceleration gains made by front-engine, rear-drive cars like its twin-turbo V8-powered M5 will not continue, and not because the new generation of turbocharged engines are anywhere near their limits.

"No, it is possible to get another 50hp, 100hp (37-74kW), sure. But what does that do to [drivetrain] reliability, and can the car actually handle the extra performance?," he said.

The performance bottleneck, admitted Ahme, is getting the engine's power to the ground.

"We are at the limit of the tyres, yes. At four seconds we are at the limit of [front-engine] rear-wheel drive traction," he said.

"When you accelerate hard from a standstill, the tyres are wheel-spinning all the way to 70-80km/h. After that, the tyres can grip and make best use of the engine power and torque. [So] raising engine performance does not mean a faster 0-100km/h time."

Acceleration times have tumbled in the last fifteen years. The current 412kW, twin-turbo V8 BMW M5 hits 100km/h from rest in 4.2 seconds, four-tenths faster than the 373kW V10 BMW M5 it replaced in 2009, which was, similarly half a second faster than mode it replaced.

Later this year BMW will introduce a mildly face-lifted M5 sedan with an extra 11kW as part of an optional performance pack that raises total power to 423kW.

Interestingly, BMW is not claiming any improvement in 0-100km/h performance.

Likewise, Australian sports sedan maker HSV is not trumpeting the accelerative credentials of the new Commodore-based GTS due later this month. The 6.2-litre supercharged V8 in the GTS makes 430kW, a whopping 105kW more than the model it replaces which recorded a 5.0-second 0-100km/h time in independent testing.

Mercedes-Benz's AMG division, BMW M's main European rival, recently unveiled an all-wheel drive version of its M5 competitor, the E63 AMG. The all-wheel drive's extra tractive effort propels the 430kW sedan to 100km/h in 3.6 seconds, a whopping six-tenths faster than the rear-drive E63 with the same engine.

BMW's M Division already has two all-wheel drive SUVs in its lineup, and is looking closely at adding all-wheel drive to its passenger car models.

"This is possible [and] we are thinking a lot about it. I can say that, but I am not saying the next model will have all-wheel drive," he said.

An all-wheel drive BMW M550d is available in Europe, but this vehicle is not considered a true M car. Rather it's a mainstream BMW model with a few M Division add-ons.

Mr Ahme says all-wheel drive may be fine for a great 0-100km/h time, but it's not necessarily what enthusiasts want.

"Under race track conditions you do not need all-wheel drive. You are always faster with rear drive once speed gets above 60-70km/h," he said.

"Maybe in slow corners you have a little bit of wheelspin... But that's fun, yes? "There's no need for all-wheel drive. Not when you have minimum extra 50-60kg at the front axle. All the time, even when it is not needed. That means also that the weight balance is not as good."

Mr Ahme has seen data that proves the current rear-drive M6 coupe can break the four-second barrier to 100km/h.

"Yes, if the conditions are perfect: a little bit cold but you have to have good traction and a good surface, the M6 can do it under four seconds.

But, he stresses, this is only achievable in optimal conditions.

"The number we quote [4.2 seconds] is achievable in a wide range of atmospheric conditions."