Just 12 months ago, the post-fossil fuel future for automotive technology seemed a largely theoretical argument of ifs, buts and maybes.

Today, its roll-out in real, ready-to-drive models has some definite diary dates, and the specific technologies that will reinvent the car as a clean, green machine are much more clearly in view.

The hybrid drivetrain, in several forms, will be one of the major technologies that keeps us mobile en route to the holy grail of automotive engineering: the zero emission car.

That vehicle may itself be a hybrid.

Existing production hybrids like the Toyota Prius use a petrol engine supplemented by an electric motor and a nickel metal hydride battery. The petrol engine drives the car and, indirectly, charges the battery. When you come to a stop, or coast, the petrol engine switches off. The car can also run for short distances – a kilometre or two – at low speed on battery power alone.

The Camry hybrid, which Toyota will build in Melbourne from early 2010, also employs this system.

It’s relatively cheap to make, there is no compromise on range, the technology is proven and it does produce results.

The next Prius, due in mid 2009, will deliver greater performance with lower consumption and emissions – probably less than 4.0L/100km and 100gkm. It will be a development of the current model’s drivetrain, with a 1.8-litre engine replacing the existing 1.5, and a more powerful electric motor.

The Australian-made Camry will use the same drivetrain as the US model, with a 2.4-litre petrol engine. Toyota claims an average consumption of 7.0L/100km (the 2.4-litre petrol-powered Camry averages 9.9L/100km) and hopes to sell at least 10,000 in the first year. Expect starting prices at low- to mid-$30K.

Honda will reprise its original petrol/electric hybrid, the Insight, with a new model in 2009. It will be similar in size to the Prius and will sell alongside the Civic, but Honda hopes for high $20K starting prices. A hybrid Jazz will follow shortly after that, then a production version of the CR-Z sportscar concept.

At the big end of town, Lexus is the only player at present. Mercedes-Benz will fit petrol/electric hybrid drivetrains to its S-Class and M-Class in 2009.

Variations on internal combustion/electric hybrid technology include micro-hybrid drive, which uses a conventional engine that has a simple automatic stop/start function and can dramatically reduce consumption in traffic. BMW employs this system on its 118i diesel (due 2009) to achieve an average of 4.5L/100km and CO2 emissions of 119gkm. Citroën also uses a micro-hybrid drive in European versions of the C3 and C2.

Diesel/electric hybrids are not far away either. Mercedes-Benz has several scheduled for production from 2010, based on its low emission Bluetec engines. The E300 Bluetec hybrid, for example, produces 165kW of power yet averages 5.1L/100km.

Citroën will have a C4 diesel/electric hybrid on sale by 2010. The current prototype averages just 3.4L/100km and produces CO2 emissions of 90gkm.

Hyundai will launch the world’s first LPG/electric hybrid, the Elantra LPI HEV, in South Korea in 2009. It hopes to export it to Australia, one of the few world markets with an established LPG industry and delivery infrastructure.

Engineers have found the battery component in hybrid drivetrains and electric cars a real challenge.

Nickel metal hydride batteries work well enough in hybrids like the Prius and Camry, which still use conventional fuels as their main energy source, but the transition from this technology – to one that uses electricity sourced from the main grid via a plug-in to drive the car, with an internal combustion engine acting only as a range-extending battery charger – demands a battery that can store much more electrical energy, withstand a squillion charge/discharge cycles, and still be compact and light enough to install in the car and leave space for people. It’s a big ask.

Enter the Chevrolet Volt, General Motors’ new plug-in hybrid that will go on sale in the US in 2010, and here, Holden says, by 2012.

The Volt is an Astra-sized hybrid, the first production model to use a lithium-ion battery as its primary power source. The battery is a big, T-shaped thing that extends across the car under the rear passenger seat, and along the centre under the floor. An electric motor drives the front wheels. The Volt has a range of up to 64km – enough to make it a viable, electric-only vehicle for many people.

Available torque of 370Nm is produced from idle, and top speed is 160km/h.

GM claims the Volt can recharge in less than three hours from a standard 240-volt outlet, and that annually it will use less electricity than your fridge.

In other words, it could cost less than four cents per kilometre.

If you need to drive more than 64km, the Volt’s 1.0-litre petrol engine will keep the battery charged and give you a range of almost 1000km. 

The Volt is the first of many second generation hybrids that will employ electric power to drive the car, with the internal combustion engine relegated to back-up generator status.

When you can recharge the battery with the solar panels on your roof, or carbon neutral power from the grid, and keep the engine topped up with bio-fuel produced from non-food sources, the zero-emission hybrid will have arrived.

Given the accelerating pace of alternative energy technology, that day may be sooner than we think.

Open Road November/December 2008