Geneva - Not too long ago car makers were still boasting about top speeds and horsepower to sell their products. In 21st century Europe it's all about grams per kilometre.
That trend was conspicuous as carmakers gathered at the annual Geneva Motor Show this week, with many labelling their shiny new cars with performance in terms of carbon dioxide emissions per kilometre.
The drive towards fuel economy and cleaner emissions has picked up momentum since the European Union struck a provisional deal late last year to cut greenhouse gas emissions from cars, setting a 130 g/km target in a phased approach starting in 2012, with full compliance by 2015.
The current EU-wide average is 158 grams.
"The CO2 interest from customers and bureaucrats is not going to go away even though gas prices have eased considerably," Jeffrey Guyton, an executive at Mazda Motor's European arm, told Reuters at the show.
"I think the market will continue to downsize, although there will be a limit to this."
Carmakers are under the gun to comply or at least come close because the upshot would be a fine on every gram of excess. Many countries also offer consumer incentives for purchases on greener cars, making mileage readings an important marketing tool.
Even Volkswagen's Bentley Motors unveiled the "flex-fuel" Continental Supersports in the super-luxury brand's first step towards making its entire fleet capable of running on renewable fuel.
The approach to reaching the emissions targets is varied and often a point of contention within the industry.
Most European brands, the long-time leaders in diesel technology, are relying largely on "clean" diesel engines, which are pricier but structurally at least 20% more efficient than a similar-sized petrol engine.
At the Volkswagen stand a blue diesel-powered Golf on display had the words "CO2 99 g/km" splashed across the hood.
Most major automakers have also joined Japan's hybrid leaders in exploring the engine-electric motor option, which Toyota Motor says is the most effective and versatile green technology.
But the war of words over the best option continues, with Daimler research chief Thomas Weber saying last week that the German automaker could improve conventional combustion engines to the point where its fleet can manage 140 grams without resorting to any electric power.
Meanwhile, even within the hybrid arena, Toyota took pains this week to distance its "full" hybrid technology from Honda Motor's simpler, cheaper but less fuel-efficient system that powers the new Insight car.
Toyota boasted that its third-generation Prius due out later this year can run 100 km on just 3.9 litres of petrol and CO2 emissions of 89 grams.
"The newest 'mild' hybrid on the market achieves just 101 grams," the Prius's chief engineer, Akihiko Otsuka, told a news conference in Geneva, referring to, but not naming, the Insight.
But as with any new technology, carmakers must strike a delicate balance between the high cost of development and production with consumers' desire for affordability.
Toyota's R&D chief, Masatami Takimoto, drove home that dilemma, calling the 130 g/km target an "extremely high hurdle".
"If you ignore the business side and hybridise all the cars, then yes, it might be possible," he said.
"Realistically, right now we have no idea how to get there."
In Europe, the new Prius is seen costing at least 9 000 euros more than the Insight, which Honda priced below 20000 euros.
At the same time, some automakers are attracting attention to their ambitions for reviving electric cars, which emit zero emissions but employ prohibitively expensive batteries.
Mitsubishi Motors, about the only carmaker with a working prototype for a relatively affordable electric car, said this week it would supply electric cars under the Peugeot brand from next year. Mitsubishi itself will also start exporting its "i MiEV" electric car from Japan in 2010.
Nissan Motor said on the same day it had agreed with the Portuguese government to consider the establishment of a lithium-ion battery plant in Portugal as it aims to mass-market electric vehicles in Europe and globally by 2012.
Nissan's partner Renault is looking to launch four electric cars between early 2011 and early 2012.
Even India's Tata Motors, which has no extensive sales network in Europe yet, showcased the electric Indica Vista EV under development.
Step by step
Until the cost of clean diesels, full hybrids and electric cars come down automakers are relying on cheaper, simpler technology that is within reach.
Fiat SpA unveiled a new system of engine valves that controls the air flow during the combustion cycle to reduce fuel consumption and CO2 emissions by 10%.
Mazda, meanwhile, is aiming to cut its European fleet's CO2 emissions by 30% by 2015 by reducing vehicle weight, improving aerodynamics and mounting a "stop-and-go" system that automatically shuts off the engine when the car comes to rest.
Daimler is planning a blanket rollout of the idling feature in Europe, while Hyundai Motor and Kia Motors also unveiled cars employing similar technology.
Jack Short, secretary general of the International Transport Forum (ITF), said that was just the kind of technology that could deliver better fuel economy without hurting the business side.
"We're not putting all the bets in an electric future," he told Reuters at the show.
The ITF, along with three other international agencies including the United Nations Environment Programme, launched an initiative to reduce cars' fuel consumption by half by 2050.