This sophisticated system also controls the Sport function. One push of the centre console-mounted button instantly changes the engine management functions, further speeding up the throttle pedal response.


Variable M differential

To deliver maximum power to the road, even when exiting the sharpest of hairpin bends, the Z4 M Coupe is equipped with the same intelligent Variable M differential that has adorned all 21st century M cars.

BMWs Variable M differential lets the driver safely explore the car's maximum capabilities by variably locking the differential's multi-plate clutch. Unlike a conventional limited-slip differential, the Variable M differential delivers power, from zero to 100 per cent, to whichever rear wheel has the greatest amount of grip. 

This is achieved by an integral shear pump in the Variable M differential that generates pressure when a difference in wheel speed is detected. This pressure pushes a piston onto a multi-plate clutch. The more pressure is generated, the more locking action is generated, up to a point where all of the available horsepower is being filtered through a single wheel.

The result? Greater lateral cornering acceleration than a car with a conventional differential or traction control system.



Three-litre Coupe - a UK first

The Z3 Coupe was only available to UK customers as an M variant. The new Z4 Coupe brings both 3.0-litre and 3.2-litre M-powered cars into the range. The badging of the new 3.0-litre engined car follows the nomenclature changes made to the recently introduced Z4 Roadster, with the car badged 3.0si. 

Having made its debut in Spring 2004 in the 630i Coupe and Convertible, BMW's unique 3.0-litre petrol engine - the world's lightest six-cylinder production engine - is the 265hp 'entry-level' Z4 Coupe model.

This peak power is generated at 6,600rpm while the red line is set at a heady 7,000rpm. The flexibility of the engine is highlighted by a peak torque figure of 315Nm available at a very usable 2,750rpm. On the road, these figures translate into a zero to 62mph sprint of 5.7 seconds and, if left unchecked, an electronically limited top speed of 155mph.
 
Drivers wanting to access the highest levels of performance from the 3.0si Coupe will reach for the Sport button. One touch activates the car's sport mode, delivering an even quicker throttle response. The characteristics of the steering also change to give a weightier, more direct feel. When the button is pressed in cars equipped with the new Sport automatic gearbox (see below), gears are changed in a higher rev range and in a much shorter time. 

But these high levels of performance are not achieved at the expense of economy. The 2,996cc Z4 3.0si Coupe features a six-speed close ratio manual gearbox as standard. This delivers 31.7mpg on the combined cycle while emitting 213g/km of CO2 emissions.
The six-cylinder in-line engine is packed with 21st century technologies. These are aimed at reducing weight and reducing the engine's own power consumption. The result? An increase in available horsepower and improved economy.

The engine block and cylinder head are constructed of aluminium and magnesium, weighing 10kgs less than the 131kgs aluminium units they replaced. The use of VANOS variable valve timing and BMW's VALVETRONIC variable valve opening technology, combined with the engine's low weight, all result in increases in output yet decreases in consumption and resultant emissions.

Additionally, unlike conventional crankshaft-driven water pumps that waste energy, the coolant in the Coupe's 3.0-litre engine is circulated using an electric water pump. This results in improved efficiency and fuel consumption, and also helps warm the cabin more quickly.

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