Geneva 2009: Golf BlueMotion

Record: New Golf BlueMotion consumes just 3.8 liters per 100 km

99 g/km CO2 sets new best value in the Golf class
Golf BlueMotion launches in June with automatic start-stop and regenerative braking

Wolfsburg / Geneva, 03 March 2009
Volkswagen is presenting the production version of the world’s most fuel-efficient automobile in its class – the new Golf BlueMotion. Average fuel consumption: 3.8 liters per 100 kilometers! Also low are its 99 g/km CO2 emissions – both values are best-in-class. At the same time, the "BlueMotion" label demonstrates that economy does not have to come at the expense of driving pleasure. This is especially true of the uncompromising and high-end design of the Golf BlueMotion.

This concept car is powered by a new quiet and high-torque common rail turbo-diesel with 77 kW / 105 kW. The innovative configuration of this 1,598 cm3 four-cylinder engine is now also the technical basis for breaking the magic 4.0 liter fuel consumption barrier in the Golf class. Furthermore, technologies like automatic start-stop and regenerative braking (energy is recovered when braking and decelerating) contribute significantly to the Golf BlueMotion’s increased efficiency. Volkswagen will introduce the new model in Europe starting in June.

The overriding goal in the development of the new BlueMotion engine was to reduce fuel consumption and CO2 emissions – which has now been achieved par excellence on the Golf – while improving performance and maximizing comfort. Anyone driving the new Golf with this engine will quickly come to understand just how successfully these goals were attained.

The excellent power response of the new 1.6 TDI is due to the fact that it already develops its maximum torque of 250 Newton-meters at a low 1,500 rpm. Fuel delivery to the engine is handled by common rail injection. Piezo actuators enable especially precise multiple injections with very high precision of fuel quantity and timing. The system operates at an injection pressure of 1,600 bar and is characterized by an optimal balance of power, refinement, acoustics and emissions.

One technical focus in the car’s development was to reduce friction power losses. Crankshaft, valve and oil pump drives were optimized. A square stroke/bore ratio minimizes friction losses at the cylinder liners. Furthermore, losses were reduced in the flow of oil and coolant, and frictional losses were reduced in air induction and charge air flows. Of course, an optimized engine cooling system also makes a positive contribution to engine efficiency.

An interesting benefit of all these efficiency improvements is that the new TDI engine is not lacking in performance by any means. It accelerates the Golf BlueMotion to 100 km/h in just 11.3 seconds and delivers a top speed of 190 km/h. Of course, this Volkswagen is also equipped with a diesel particulate filter. Like all sixth generation Golfs, the BlueMotion model also meets the limits of the new Euro-5 emissions standard.

BlueMotion – clever mix of technologies
The astonishing fuel economy of the latest Golf version is achieved with further modifications that are in addition to those already mentioned concerning the engine. As with other BlueMotion models, these include rpm-reducing gear ratios (a five-speed transmission is employed here), very low rolling resistance tires and special aerodynamic refinements. For the first time, these improvements are being supplemented by a start-stop system and regenerative braking.


Start-stop system in detail
Especially worthwhile is a look at the fully intuitive operation of the start-stop system. The driver approaches a red light in the Golf BlueMotion, brakes the Volkswagen to a stop, shifts to neutral (ideally this is done on a conventional car too) and takes his or her foot from the clutch. This shuts off the engine momentarily. A "Start Stop" message now appears in the multifunctional display. As soon as the traffic light turns green again, the driver fully depresses the clutch, the engine starts, the "Start Stop" message disappears, the driver puts the car back in gear and resumes driving. Essentially, the driver does not need to perform any additional steps compared to a conventional car, yet the start-stop system saves up to 0.2 liter of fuel per 100 kilometers on average in city driving.

Regenerative braking in detail
Regenerative braking helps to utilize energy that would otherwise be lost in driving as beneficially as possible. During deceleration and braking phases of the Golf BlueMotion – i.e. whenever the driver simply releases the gas pedal or intentionally brakes – the alternator’s voltage is boosted, and this is utilized for bulk recharging of the vehicle battery.

Thanks to alternator control – which regulates the alternator as a function of engine efficiency for optimal battery charging – it is possible to reduce the alternator voltage, e.g. when accelerating or driving at a constant speed. It is even possible to switch off the alternator entirely. This reduces engine load and improves fuel economy. Special software for energy management and modified engine control software are needed to utilize regeneration.