While Mercedes can boast the world’s most technologically advanced car, Volkswagen can now lay claim to the most fuel-efficient production car, which is soon to go on the market.
For more than five years VW has been working on the production of its so-called ‘3-litre car’ a name that refers not to the engine size but to its fuel consumption: three litres per 100km, equivalent to about 93 miles per gallon.
This month at the Paris Show, VW showed that its dream looks set to become reality. From early next year, the Wolfsburg plant will start production of a variant of the Lupo that it claims will sip just 2.99 litres of diesel for every 100km travelled, measured by standard fuel consumption norms.
The surprise in all this is that there is no earth-shattering technical leap involved here. And when the car goes on sale in Germany, it will cost DM26,000 (£9,200), or only about £2,000 more than a standard Lupo.
The engineering of the car is based on two key developments. The first is weight reduction, using special steels, as well as magnesium and aluminium. The other is the drivetrain, involving a three-cylinder turbo diesel unit coupled to an automated clutch manual transmission.
A normal all-steel Lupo weighs from 960kg. The 3-litre Lupo has shed 180kg of this. Aluminium and magnesium use in the body panels and thinner steel have saved 60kg.
Laser welding has been used for the sill areas, while use of alloys for the subframe and running gear have reduced the weight by a further 60kg. The engine crank case and cylinder head are also cast in aluminium.
The engine is derived from VW’s new generation of ‘pump spray’ direct injection diesels, which have one unit injector per cylinder, with a working pressure of up to 2000 bar. In this model, a three-cylinder 1.2-litre unit is used, which delivers up to 61bhp at 4,000rpm.
Maximum torque of 140Nm is available, making the car flexible to drive as well as being cheaper to run. VW claims a 0 100km/h sprint in 13.9 seconds.
Emissions, too, are very low. Compared with a conventional 1.6-litre petrol engine, the small diesel puts out 75% less hydrocarbons and 85% less carbon monoxide.
The economy of the Lupo owes as much to its transmission as it does to the engine. Volkswagen has opted for an automated direct shift gearbox.
This is similar to a clutchless manual gearbox, but with the added feature of a self-shifting mode to optimise fuel economy. It also has a tiptronic mode, which is less economical, but allows the driver to change up and down simply by flicking the shift lever forwards or backwards.
The self-actuating gearbox is coupled with a stop-start system. This will cut the engine after four seconds of idling in stationary traffic with the footbrake activated and then restart it when the accelerator is touched. The system is an improved version of the one introduced on the Golf Eco in four years ago.
VW will build the 3-litre Lupo in small volumes on a new production line to be added alongside the normal Lupo line at its plant in Wolfsburg, Germany.
‘We are not making money from this car, but we are not losing money either,’ says Karl Taylor, product manager for the Lupo. ‘This is a technology carrier for the whole VW group, and we will see benefits from this car on other models.’
With Lupo production next year scheduled for 150,000 vehicles, the ‘few thousand’ planned for the 3-litre version looks modest. Taylor says the car should be as good a proposition for the public as the MCC Smart.
‘That car is a two seater,’ says Taylor, ‘and one car magazine test put its fuel consumption at 5.8 litres per 100km almost double that of the Lupo, which is a four seater. That makes this car look very attractive.’