238mpg

[GasSavers_Antoine]

June 5, 2002

Feature: VW 1-Litre-Car
by Greg Wilson

The most economical car in the world

A few years ago, Volkswagen took on a task that many people thought was impossible: they decided to develop a fuel-efficient, road-going compact car that could achieve an average fuel consumption of just 3 litres per 100 km (94 mpg). Not only did Volkswagen achieve this milestone in 1999, but they had an even larger goal in mind: an ultra fuel-efficient car with a super stingy fuel consumption rating of just 1 litre per 100 kilometres (282 mpg).

After three years of development in secret, the 1-Litre-Car was unveiled in April in Hamburg, Germany at Volkswagen’s annual stockholders meeting. To prove that it is a viable, road-going automobile and not just a pie-in-the-sky concept, VW Chairman Ferdinand Piech himself drove the 1-Litre-Car from Wolfsburg to Hamburg to join the shareholders meeting - averaging just 0.89 litres per 100 km (317 mpg) along the way.

To design a car with such incredibly low fuel consumption, Volkswagen engineers had to literally go back to the drawing board – they threw out most off-the-shelf body and powertrain solutions, and started with a blank slate.


Proper aerodynamics were key to the low fuel consumption. VW engineers knew they needed a small frontal area – this led to its unusually narrow, bullet-shaped body where the passenger sits behind the driver. As well, the car features an aircraft-like canopy, enclosed rear wheels, special flat carbon-fibre front wheel covers, and an aerodynamic underpan. Even the side cooling air inlets only open when the engine needs cooling, and otherwise stay closed. At 3.47 metres (11.4 ft.) long, 1.25 metres (4.1 ft.) wide and just over a metre (3.3 ft.) in height, the 1-Litre-Car has an amazingly low coefficient of drag of 0.16 (a typical car has a drag coefficient of approximately 0.30 ).

Exterior mirrors weren’t even considered because of air drag. The 1-Litre-Car has cameras in the side turn signals and two small LCD monitors left and right of the circular central instrument. For parking, a centrally-mounted rear-view camera in the third brake light shows the area directly behind the vehicle.

The 1-Litre-Car is also extremely light, weighing just 290 kg (640 lb.): that’s less than one third of the weight of a 2002 Toyota Echo. The 1-Litre-Car’s body is made completely of carbon fibre composites, and to save weight, it is not painted! Its carbon-fibre-reinforced outer skin is tensioned over a spaceframe that is made of magnesium, which is even lighter than aluminum.

VW engineers also knew they needed a small, fuel-efficient engine – but how small? 3 cylinder and 2 cylinder engines were considered but were quickly dismissed because they weren’t capable of reaching the 1 litre per km goal. VW engineers also quickly realized that a diesel engine was the only real option for the powertrain as only a diesel meets the maximum requirements for optimum energy utilization.

The one-cylinder SDI engine in the 1-litre car is not a derivative of an existing engines, but a completely new, technically sophisticated powerplant. The naturally aspirated, direct-injection diesel engine employs high-pressure unit injection technology to generate 8.5 horsepower at 4,000 rpm and maximum torque of 18.4 Newton metres at 2,000 rpm. The crankcase and cylinder head of the 0.3-litre engine are of an aluminium monobloc construction. Two overhead camshafts actuate roller rocker fingers which in turn actuate three valves, two inlet valves and one exhaust outlet valve. These are then fed from the engine through a titanium exhaust system with reduced backpressure.

With a 6.5-litre fuel tank and an average fuel consumption of 0.99 litre per 100 kilometres, the 1-Litre-Car has a range of more than 650 kilometres (400 miles). To save fuel, the engine shuts off when the car is stopped at a traffic light, and when the driver takes their foot off the accelerator pedal. The car will roll freely without the engine running and start up again immediately when the magnesium accelerator pedal is depressed.

The engine is positioned just ahead of the rear axle and is mated to an all-new 6-speed manual transmission that shifts automatically. The gears are electro-hydraulically actuated, eliminating the need for a shift lever and clutch pedal. Gear selection - forwards, reverse or neutral - is made using a turn switch on the right-hand side of the cockpit. To save weight, the transmission housing is made of magnesium, all gears and shafts are hollow, and bolts are made of titanium. The 6-speed gearbox weighs a mere 23 kilograms.

The suspension is also made of lightweight materials. The front double-wishbone axle is made of lightweight magnesium and aluminium, the wheel hubs are made of titanium, and the balls in the lightweight construction wheel bearings are ceramic. The entire front axle unit weighs just 8 kilograms (18 lb.) The De-Dion rear axle has leaf springs made of glass fibre, a transverse tube and wheel mountings of aluminium, and the wheel hubs of titanium.

Direct mechanical steering, featuring a flat-top steering-wheel (whose magnesium skeleton gives it a weight of only 540 grams) is also extremely lightweight. The steering box and rack is made of magnesium, aluminium and titanium.

All four wheels have disc brakes made of lighweight alloy and include an anti-lock brake system. The 16 inch wheels are made of a carbon fibre composite which is 50% lighter than a traditional wheel and include low-friction wheel bearings. The car’s unique low rolling resistance tires reduce rolling resistance by up to 30%.

Despite its small size and light weight, Volkswagen says the 1-Litre-Car is as safe as a GT sports car registered for racing. With the aid of computer crash simulations, the car was designed with built-in crash tubes, pressure sensors for airbag control, and front crumple zones. Its aluminium fuel tank is located in a protected area behind the passengers. As well, the 1-Litre-Car includes ABS and ESP (electronic stability program).

The interior, though spartan, has all the basics and room for two people sitting in tandem. The driver looks over the flat-top steering-wheel, and to the left and right of the central circular instruments are the monitors with pictures from the two rear-view cameras. On the right side of the dash is a turn switch for gear selection, the electric parking brake, and the starter button; on the left are the heating and ventilation controls, and headlight switch. The passenger puts his/her feet on footrests located on the sides of the driver’s seat. There is even an 80 litre stowage compartment under a flap in the rear.

Volkswagen believes the 1-Litre-Car could lead to a new family of vehicles, ranging from the ultra-economical commuter vehicles, to low-lost everyday touring vehicles aimed at young people, to high-performance sporty cars. The 1-Litre-Car is certainly an interesting alternative to a motorcycle, and could prove popular in regions of the world where fuel is expensive and small, inexpensive cars are in demand. Whether North Americans would embrace such a small car is questionable – price would be a major factor. It would certainly have the ‘Wow’ factor on its side. This is probably the coolest economy car ever built.

Greg Wilson is editor of CanadianDriver.com.

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