Want one of these? Prepare to charge

The Flextreme ‘series’ hybrid is as green as it gets, says GM. So, could this plug-in concept be the future? Rebecca Wright finds out

(Opel)

The GMFl extreme concept car and its elder sibling, the Chevrolet Volt, showcase technology that is splitting the opinions of the big boys of the global car industry.

General Motors is putting a huge amount of faith into this range of cars, suggesting that they will reach mass production by 2010. If achieved, this would be a real coup on GM’s behalf. On the other hand, top-level executives from other car companies – most notably some of the Japanese – have gone on the record expressing their scepticism about such vehicles.

The Flextreme is the European version of the Chevrolet Volt – one of the most talked about concept cars of 2007. The cars are best classed as “series” hybrids and their primary energy source is a lithium ion battery. Under normal commuting use, the battery is plugged in to mains electricity to recharge, although it also recovers energy while driving – from braking, for example. Using only the battery, the Flextreme and Volt have a range of 34 miles, which, says GM, is within the needs of most European commuters. In turn, this means travelling to work and back without creating any CO2 emissions on the road.

For those that do drive more than 17 miles to work (or 34 miles if they are able to recharge in the company car park), the Flextreme has a fairly regular 1.3-litre turbodiesel engine, similar to the one found in today’s rather more mainstream Vauxall Astra and Corsa cars. The Volt, which is targeted at the US market, has a 1.0-litre flex-fuel bioethanol/petrol engine. But the difference between these series hybrid cars and conventional “parallel” hybrids is that the internal combustion engine is not connected to the wheels of the car and so never directly powers the vehicle, as with cars such as the Toyota Prius and Honda Civic Hybrid.

Instead, the engine is connected to an electricity generator. This recharges the battery if and when itruns out of power while driving. The internal combustion engine thus acts as a back-up, offering the potential to extend the car's operating range to 445 miles. GM calls this technology “E-Flex”.

The main advantage of the diesel or petrol engine being used to recharge the battery is that electric vehicles use their energy far more efficiently than cars with internal combustion engines (ICE). An electric car typically runs at above 90 per cent efficiency across the driving range, from hard acceleration to cruising. Cars powered by an ICE reach a maximum of 35 per cent efficiency if they’re cruising at 60mph in steady motorway conditions, but this can slump to as little as 2 per cent efficiency in other driving conditions, such as stop-start in cities, or driving that involves a lot of hard acceleration and braking. So less fossil fuel will be used to recharge the battery than would be used to directly power the car.

Despite these benefits, rivals take exception to aspects of GM’s strategy. One of the most contentious issues is whether to plug in or not. While most car companies, policy-makers and even environmental groups seem to agree that “electrification” is the way forward – at least until the holy grail of fuel cells is obtained – there is less consensus about how the electricity should be generated.

Plug-in hybrids displace their CO2 emissions from the car to the source of the electricity. This was highlighted in the King review, a government-funded study designed as a road transport follow-up to the widely quoted Sternreview, which said: “While such vehicles will have zero CO2 emissions on our streets, they will rely on clean electricity to provide truly low-carbon transport.” The study said that in the UK only 4 per cent of electricity comes from renewable energy and 18 per cent from nuclear power, leaving 78 per cent generated by fossil fuels.

GM and others point to the economies of scale that come with mass electricity production. It is far more efficient to produce electricity on a large scale in one place, even if it is from fossil fuels, than to have lots of individual generators, whether they be cars running on fossil fuels or cars running on batteries that do not need to be plugged in.

The main focus of debate, however, relates to GM’s stated timelines, especially as far as the development of lithium-ion batteries goes. Although in widespread use, the cells are generally in items such as laptops and mobile phones. Experts say a lithium-ion battery large enough to be the energy source for a car used in everyday driving conditions, such as the Volt and Flextreme, would have to be so large that it would fill the boot of the car. Not only that, but the cost of such a battery would be astronomical, far more than GM could afford to put in a car of Vauxhall Astra size and type. Batteries of such magnitude are also unproven – reports from Japan talk of lithium-ion test cars bursting into flames as their batteries have overheated or shortcircuited. Lithium-ion technology far from ready for the application General Motors has in mind.

GM has admitted to The Independent that because its suppliers are still developing the batteries, it has not yet tested these cars with batteries in them – but that that work is due to start soon. The company also said that it may initially sell the car but lease the battery, which would enable it to continually refine and improve the technology. Such a strategy would also allow GM to sell the car far more cheaply than it would otherwise be able to do. Even if this option were pursued, GM admits that the carwould still have to retail for more than vehicles of a similar size running on conventional fuel. At the moment, a price premium of around £3,000 looks likely.

Andrew Close, a technical research analyst from automotive forecasters and consultancy Global Insight sums these issues up: “Whenall’s said and done, the GM Flextreme as a plug-in serial hybrid with a small diesel engine is about the most CO2-efficient car that can be built today. The debate should be whether or not the extra cost of hybrid components and lithium-ion batteries justifies the extra CO2 performance of this car over a small conventionally fuelled diesel engine whose CO2 emissions are already very competitive. I do not see this cost equation making sense in Europe without massive increases in fuel prices or CO2-based road taxes. While this might be the case in 10 years’ time, we might have fuel cells by then,” Close says.

He does acknowledge that once thecosts over the lifetime of the car are taken into account, the cost analysis could be more favourable for the Flextreme. This means that much, if not all, of the extra purchase price of a plug-in car would at some point be offset by the money that is not spent on petrol or diesel during the ownership of the car, even when taking into account the price of recharging.

Close also highlights the environmental cost of the production of a car such as the GM Flextreme. So while that car, just like today’s hybrids such as the Prius, are complicated to make, a Fiat Panda or Peugeot 207 with a small diesel engine is not. When taking these factors into consideration, the overall CO2 impact of allhybrids and electric cars is raised.

The story is very different in the US and Japan, where diesel engines barely exist and relative CO2 emissions from road transport are higher than in Europe. And this is the beauty of E-Flex technology – that it does allow GM to hedge its bets and develop different solutions for different parts of the world within one car, to a certain extent.

GM should be applauded for sticking its neck out and putting its reputation on the line with the Volt and Flextreme, as well as devoting considerable investment and resources to them. Earlier this year, GM’s Bob Lutz said that $100m had already been spent on this project. It’s a bold move that most of the company’s rivals have not been brave enough to make, despite their stated intentions of eventually launching equally clean electric cars. So GM seems ahead of its rivals on plug-in lithium-ion battery technology, even if it still has a long way to go with the costs.