The jury might still be out on whether or not plug-in vehicles will eventually be widely accepted but what is not in doubt is the high level of R&D investment going into them worldwide. But where does this leave pure hybrids, or indeed mild hybrids, plug-in hybrids and General Motors’ extended-range EV powertrain? In the first of a three-part series, Glenn Brooks examines the latest alternate powertrain technology.

The car that took series hybrid powertrains into the mainstream, the Toyota Prius , is now well into its third generation and continuing to evolve. Sales might be down in both Japan and the US from the record numbers that were registered in 2009 and 2010, but Toyota is continuing to aggressively promote the technology. Soon, a five-door Prius MPV will be launched in North America, Europe and Japan, to be joined in at least two of those regions by a petrol-electric version of the Vitz/Yaris hatchback.

The main Japanese brand rival to Toyota’s hybrids has always been Honda. For various reasons, the company has not enjoyed anywhere near the success of its larger competitor, especially with the Insight hatchback. Now, the firm is trying a different approach, launching multiple smaller models in an attempt to catch Toyota. The CR-Z is aimed at those who want a sporty car but feel the need to make a ‘green’ statement, while the Fit Shuttle, a small MPV sold mostly in Japan, is aimed at those who like the idea of the smaller Fit Hybrid but need a bit more space.

American manufacturers have also started to catch hybrid fever, though their ambitions are more modest than those of Toyota and Honda. A one-off factor is also proving to be the cause of falling sales of hybrid vehicles in California, the traditionally largest market for cars with gasoline-electric powertrains. There, the ending of an exemption for hybrid vehicles with only one occupant using carpool lanes has seen a big fall in sales of such vehicles in recent months.

Ford, which has only ever been a small player in the US market for hybrids, has started to tout the official average fuel consumption numbers for its Fusion Hybrid sedan. The result has been a strong rise in sales of the car throughout 2011. The timing was also fortunate for the company as supplies of parts for the rival Toyota Camry Hybrid slowed dramatically following the tragedy that befell Japan in March.

Recently, Japanese manufacturers have more or less got their supply chains fully back up to speed so it will be interesting to see if cars such as the petrol-electric versions of the Ford Fusion, Hyundai Sonata and Kia Optima can maintain their recent sales momentum in the US market. They do look like they will have a fight on their hands, however, as Toyota is currently preparing to launch an all-new Camry Hybrid.

In markets outside the US, Canada and Japan, sales of hybrid and electric vehicles continue to be modest to small. Across Europe, for example, the Prius is well known but equally it is overlooked by the majority of buyers who instead choose a smaller and crucially, cheaper, diesel-engined car.

The same problem applies to the new breed of electric models that continue to be launched in the region. The Nissan Leaf and Mitsubishi i-MiEV are becoming increasingly well known but still they remain expensive to buy, plus the distance available on one charge can be a big issue for many potential buyers, as can be the problems of recharging for those without a garage.

Perhaps more promising for many drivers are GM’s plug-in twins, the Chevrolet VOLT and forthcoming Opel/Vauxhall Ampera. The company is aiming to build a combined 60,000 units of these cars in 2012, of which 2,000 Volts and 10,000 Amperas will be shipped to Europe from the plant in Michigan that builds all three models. GM China will also launch the Volt later in 2011 but the numbers to be sold in that market should remain small due to the high level of taxation applied to all imported cars.

China itself is often cited as the one country where hybrid, plug-in hybrids and pure EVs will one day take off in a big way but thus far, that day seems to be firmly set into the distant future. Of the many indigenous manufacturers, BYD has made the largest investments in alternate energy powertrains, yet it has failed to sell many such models in either its home market or abroad. Ironically, the petrol-engined version of the BYD F3, a small sedan, has been hugely successful, with just under 113,000 units sold at home in the first half of this year.

BYD’s F3 DM (Dual Mode), which combines a 1.0-litre petrol engine with an electric motor, is claimed to have a range of 100km silent running before it needs to be recharged. Like the larger and more sophisticated Nissan Leaf in European markets, the F3 DM is pricey and so sales have been small. Indeed, the company built only around 100 units of the F3 DM at first, placing these with governmental agencies. Sales to the general public followed from March 2010, with the car initially only available for purchase in Shenzhen. Still only a small number of cars has been sold.

Perhaps a more promising technology for many buyers, or those with a decent budget at least, is diesel-electric, as pioneered by PSA Peugeot Citroen with its HYbrid4 system. This powertrain is now available in a special range-topping version of the 3008 MPV, and will also feature in the 508 RXH, a new crossover based on the 508 wagon that is set to be unveiled at next month’s Frankfurt motor show.

HYBrid4 is of particular interest for its ability to operate as a 4×4 system. In the 3008, the front wheels are driven by a 120kW (163bhp) 2.0-litre diesel engine, with rear wheel drive provided by an electric motor. Torque is an impressive 500Nm, while total power is claimed to be 200bhp. The driver can select any of four different modes, one of which allows electric-only power (though the diesel engine will kick in under hard acceleration), while another activates both power units if constant four-wheel drive is required. A plug-in variant of the 3008 HYbrid4 is due to be launched in 2012.

Now that PSA has begun to open up the European market to the possibility of diesel hybrids, Mercedes-Benz is betting that its new ML 250 BlueTEC might well do the same for larger SUVs. The brand has just announced its third generation M-Class and among the model variants is the first four-cylinder version. While it will be US-built, as yet the company is not saying if it will sell the diesel-electric engine there. According to preliminary statistics, the ML 250 CDI will be powered by the combination of a 201bhp 2.1-litre I4 turbodiesel and a 20bhp electric motor.

Like Daimler and PSA, the Volkswagen Group is for now using premium pricing for its hybrid models. Following on from the Porsche Cayenne and VW Touareg Hybrid twins which are built alongside one another at the Bratislava plant in Slovakia, Audi will soon launch three petrol-electric models: the Q5, A6 and A8 hybrids. The Q5 looks like being the first to hit the market and will be distinguished from the A6 at least, for having standard quattro all-wheel drive.

Audi’s cautious approach to hybrids can be seen in the fact that it is using one powertrain for all of its three models. This is a 155kW (211hp) turbocharged direct injection four-cylinder 2.0-litre gasoline engine (‘2.0 TFSI’), that is boosted by a single 33kW (45hp) electric motor. The combined torque is, Audi claims, 211Nm. Audi says the system gives the Q5 hybrid quattro a 3km range on electrical power alone.

As can be seen by each of these examples, the market for hybrids, plug-in hybrids and pure EVs continues to expand and evolve. The major global manufacturers are closely watching one another as well as each new innovation to see which, if any, catches buyers’ imaginations. Just what each of these vehicle makers is planning to launch next will be the subject of the second of the three articles in this series.