The Passat comes equipped for the first time with a 4MOTION system featuring Haldex coupling. The coupling, which is fitted directly in the rear axle, is considerably more compact and the system works quickly, sensitively, and quietly. As a general rule, four-wheel drive beats rear-wheel drive especially in the wet or on ice and snow. Besides that, even on dry roads 4MOTION improves cornering forces for better active safety. There are known reasons why: 4MOTION’s electronically controlled system provides the best possible distribution of force to all four wheels, varying it to suit the road conditions and the levels of grip.
The 4MOTION System
The central element of the 4MOTION system is the latest generation of multi-plate wet coupling (in an oil bath). It is called the Haldex coupling as it was developed together with Swedish systems partner Haldex who have worked with Volkswagen for many years. The Haldex coupling has the major advantage of being electronically controlled. This allows it to work very effectively in conjunction with the anti-lock braking system (ABS), the traction control system (TCS), the electronic differential lock (EDL), and the electronic stability programme (ESP) - all these assistance systems are fitted as standard in the Passat.
The axles are "coupled" by pressure: as soon as differences in the speeds of rotation between the front and rear axles occur, two annular piston pumps within the coupling are activated which build up pressure in the multi-plate coupling, thus "coupling" the two axles to each other. The only go into action when the input and output shafts are no longer turning at the same speed. Only then is it necessary to adjust the torque distribution.
The rear axle always receives at least 10 percent: the transmitted torque can be varied by adjusting the pressure on the coupling plates, thus controlling the flow of power between the front and rear axles. The coupling provides infinitely variable torque adjustment between the front and rear axles. In extreme cases up to 100 percent of the available torque can be transmitted to the rear axle. In the normal case with the vehicle travelling in straight line at a constant speed with no differences in the wheels’ grip, 90 percent of the torque produced is transmitted to the front axle and ten percent to the rear axle. The Haldex coupling is driven by a propshaft.
The CAN bus makes it all possible: The coupling’s electronic control unit is fed with all relevant drivetrain and engine information via a CAN bus. This includes signals from the wheel sensors, the ABS and ESP, plus information on the accelerator pedal position and engine revs. Based on these data the 4MOTION control unit controls the level and changes in hydraulic pressure acting on the coupling plates. The coupling responds to "commands" from the 4MOTION electronic control unit extremely quickly. The compact coupling also has a very robust design and can transmit a torque of 3 200 newton metres to the rear axle.
4MOTION plus the 147Hp 2.0 FSI - The 2.0 FSI is a four-cylinder petrol engine capable of delivering 147 HP (at 6 000 rpm). At 3 500 rpm it produces its maximum torque of 147 lbs-ft. In the saloon version the 1 984 cc direct injection engine can accelerate the Volkswagen Passat to 60 mph in 9.8 seconds and reaches a maximum speed of 130 mph. The values for the four-wheel drive estate are 128 mph and 10.2 seconds. The Passat 2.0 FSI always comes with a manual six-speed gearbox. In the combined driving cycle the saloon consumes an average of 8.7 and the estate 8.9 litres of fuel per 62 miles.
4MOTION plus the 246 Hp 3.2 V6 FSI - The new top model in the range, the Passat 3.2 V6 FSI, is supplied with 4MOTION and the DSG dual clutch gearbox as standard. At 6 250 rpm the six-cylinder direct injection petrol engine delivers 246 Hp. It develops its maximum torque of 236 lbs-ft at 3 200 rpm. The advantages of direct injection are more output, better fuel economy and lower emissions. An extensive array of new calculations were undertaken to give the V6 FSI optimised stiffness properties, a lower level of component stress, and a lighter weight.
The 3189 cc engine propels the Passat saloon from nought to 60 mph in just 6.8 seconds, while the estate needs just a tick longer at 7.2 seconds. Both body versions of the Passat can reach well over 149 mph); the saloon hits maximum at 153 mph, the estate at 151 mph. The top Passat models use an average of 9.8 litres (saloon) and 10.0 litres of fuel in the combined cycle.
The DSG in the new Passat 4MOTION has six forward gears and shifts extremely fast with no power interruption. This gearbox - like Volkswagen’s classic Tiptronic - allows manual gear changing using the "plus" and "minus" shift gate.
4MOTION plus the 138 HP 2.0 TDI - A top speed of 127 mph is possible in the saloon version of the Passat 2.0 TDI 4MOTION, which produces 138 HP at 4.000 rpm, while the estate is capable of 125 mph. The four cylinder engine is supplied in combination with a six-speed gearbox. The 2.0 TDI develops a maximum torque of 236 lbs-ft between 1 800 and 2 500 rpm and accelerates the saloon to 60 mph in 10.2 seconds (estate 10.5 seconds). The average fuel economy in the version with optional diesel particulate filter: 6.7 litres and 6.8 litres (estate) per 62 miles.