World Green Car 2008

In the current debate about when and how we should move into the post fossil fuel transport era, it's easy to lose sight of the fact that existing technology also offers great scope for short term improvements in efficiency and performance, and that many car makers are already delivering significant gains.

In the past decade, for example, carbon dioxide emissions - the main contributor to global warming - have been reduced by an average of 55 per cent in petrol engines. In diesels, the reduction is 92 per cent. Other gaseous emissions have been reduced by 70-81 per cent. Diesel particulate emissions are 98 per cent less than they were in 1998.

What this means is that you can buy clean, green cars right now. It's not just a future game - if you're in the market for a new car, you can choose one that's environmentally friendly, in the same way as you can buy your electricity from a renewables supplier, or install a rainwater tank.

The World Green Car award, which was announced at the New York International Auto Show on March 20, 2008, is an annual snapshot of current environmentally-focussed car technology.

Nine of the ten finalists are available in European and American showrooms now, but at the time of writing only one - the Lexus LS600h L - is available in Australia.

Let's look at the World Green Car 2008 finalists in more detail.

BMW 118d with Efficient Dynamics

BMW has long been serious about maximising the efficiency of its powetrains, which are usually at or near the front of their respective classes in fuel economy and emissions. Part of the reason for this is BMW's parallel engineering creed of minimising weight. The heavier the mass, the more energy is required to move it.

Efficient Dynamics is BMW's new catchphrase for its environmentally focussed engineering efforts. It encompasses everything from maximising fuel economy in conventional petrol and diesel engines, developing low rolling resistance tyres and electric steering systems to BMW's involvement in exploring to possibilities of hydrogen as the fuel of the future.

The new 118d, for example, has a 2.0 litre four cylinder direct injection turbodiesel engine that produces 16 per cent more power (105kW) than its predecessor, yet averages 16 per cent less fuel consumption - an average of just 4.7 litres/100 km. CO2 emissions are a low 119g/km. Brake energy regeneration and auto start/stop contribute to these gains.

Chevrolet Equinox Fuel Cell Electric Vehicle

General Motors has staked most of its post fossil fuel engineering on fuel cells thus far, but it is now also pursuing hybrids, as these look like a more viable option in the short-medium term at least.

Fuel cells combine oxygen from the air and hydrogen carried in an on-board tank. The resulting chemical reaction produces electricity, which drives the car. The only by-product is harmless water vapour.

The Equinox is a developmental prototype vehicle, with more than 100 now on the roads in the US being trialled by customers, in an exercise called Project Driveway. The project will be extended to Europe in 2008 with around 10 cars.

The Equinox is engineered for a life of around 80,000 km. It also meets all current safety standards.

Chevrolet Tahoe/GMC Yukon Hybrids

The Chevrolet Tahoe/GMC Yukon hybrids (same car, different General Motors badges) have evolved from a system GM first used on buses.

The Tahoe and Yukon are largish (by Australian standards) production SUVs, with a 6.0 litre V8 engine based hybrid system that has two modes for city and highway driving. The V8 itself can also run on four cylinders when performance isn't imperative (in traffic, for example); hybrid modes include full electric or any combination of petrol and electric power.

GM claims a 50 per cent reduction in fuel consumption over the relevant conventional petrol engine counterparts. It's quoting 21 miles per gallon in town.

Saturn Vue Green Line Hybrid

The 2008 Saturn (another GM brand) is the most economical SUV in the US. It's overall average fuel consumption of around 9 litres/100 km is pretty ordinary by Australian standards, but it should be noted that diesel is not a mainstream passenger car/SUV fuel in the US.

It's a production vehicle, priced at around $30,000 (Australian), which goes up against Toyota's RAV4 and the Honda CR-V in the American market.

The Saturn matches a 2.4 litre four cylinder petrol engine with an electric motor, four speed automatic and front-wheel drive.

The hybrid system includes engine off at idle, low speed electric only propulsion, electric boosting during strong acceleration, hill climbing or towing, cutting off fuel to the engine during deceleration, regenerative braking and engine speed and load control.

Saturn Aura Green Line Hybrid

Basically the Saturn Aura sedan - a Toyota Camry/Honda Accord competitor in the US - with the same 2.4 litre hybrid powertrain as the Vue SUV, the Aura Green Line is the lowest priced hybrid car in the US, where it costs around $25,000 Australian.

Its drivetrain produces 122kW of power and 215Nm of torque. It averages around 9 litres/100 km in city driving and is a five star USNCAP scorer.

Chevrolet Malibu Hybrid

This Commodore sized sedan also uses the 2.4 litre hybrid drivetrain from the Saturn range.

Lexus LS600h L

Based on the LS460 sedan, the LS600h L, priced from $233,000, uses a 5.0 litre V8/electric motor hybrid drivetrain which sends power to all wheels via a continuously variable automatic transmission.

The combined power output of the hybrid system is 327kW. The LS will reach 100 km/h in a claimed 6.3 seconds, and averages 9.3 litres/100 km, with CO2 emissions of 219g/km, according to Australian standard tests.

It's also got a few party tricks, such as being the first car than can park itself, and the same levels of quality, luxury and even more equipment than the LS460.

Some have argued that the LS is an example of "greenwash," a product that's being spun as environmentally friendly when in fact it's not. Given that it weighs 2375-2430 kg - more than most big 4WDs - they may have a point. 

Nissan Altima hybrid

A North American market model, the Altima hybrid competes with the Camry and Saturn. It has a 2.5 litre four cylinder petrol/electric motor/CVT hybrid drivetrain and averages 6.7 litres/100 km in town.

smart fortwo cdi

This sits at the opposite end of the enviro-car field to the Lexus. Launched in Europe in 2007, this is the latest version of the cute, clever - and hugely unprofitable - smart, the little two seater hatch that's quite a common sight in European cities like Paris and Rome, where owners can park in many places that are just too tight for normal cars.

The cdi uses a 33kW/110Nm, 800 cc turbo diesel that averages just 3.3 litres/100 km and emits 88 g/km of CO2 - that's 18g/km less than a Prius hybrid.

It has the lowest fuel consumption and the lowest CO2 emissions of any production car.

Volkswagen Passat 1.9 TDI Blue Motion

Blue Motion refers to a process whereby the noxious gas emissions from turbodiesel engines are minimised. It's an evolving technology with low sulphur diesel fuels - lower than we have in Australia - used at present by Mercedes, Audi and VW.

You will be familiar with the Passat, a mid size family car, also available as a spacious wagon.

The Passat Blue Motion's 77kW 1.9 litre turbodiesel averages 5.1 litres/100 km and produces 136g/km of CO2.

It features optimised gearing, a lower idle speed, a slippery underbody for better aerodynamic performance and low rolling resistance tyres.

By Bill McKinnon, January 2008.