With a price tag of about Rs 1 lakh, the Nano will cost about half as much as the cheapest car currently on the market. But, some environmentalists are dreading the prospect of hundreds of thousands of low-cost cars hitting polluted and over-crowded roads around the world in the next few years. "In the current policy and regulatory framework, the low-cost cars will be disastrous," said Anumita Roychowdhury, Associate Director of the Centre for Science and Environment in New Delhi. Carmakers in developed markets argue that the small, fuel-efficient vehicles are a greener option than gas-guzzling SUVs and larger cars as consumers in emerging economies such as China, India and Russia buy cars. Tata Motors says the Nano meets the strictest environmental criteria, and its lean design delivers high fuel-efficiency of about 20 km/litre of petrol. The car will have tailpipe emissions well within Indian requirements. It is less polluting than motorbikes and scooters, the company says on the Nano's website. "The concern is really about the sheer numbers," said Mohit Arora, managing director for India at JD Power Asia Pacific. "They may be more fuel-efficient than bigger cars, but they will still emit carbon and NOx (nitrogen oxide), and that's a valid concern," he added. Every day, about 17,000 private vehicles are being added to China's already congested roads, while Indian passenger vehicle sales are expected to rise by almost 50 per cent over the next three years. Such explosive growth will demand a rethink from automakers. Indian motorbike maker Bajaj Auto says its $2,500 car, which it is building with Renault and Nissan Motor, will aim at a fuel-efficiency of 30 km/litre, or twice an average small car, and carbon dioxide emissions of 100 gm/km. "That would make it far superior to cars even in the European Union, which wants to bring down carbon emissions to 120 gm per km (from 2012), and the 180 gm/km that India is fighting to defend," said managing director Rajiv Bajaj. The Bajaj venture will have an initial capacity of four lakh units, while Tata expects eventual demand of 10 lakh Nanos. Rival carmakers including Fiat, General Motors, Ford Motor, Hyundai and Toyota Motor have all expressed interest in building a small car that is affordable to more middle-class consumers in emerging markets. But not everyone is sold on the small and super-cheap car. "I don't see the draw of that kind of car," Honda CEO Takeo Fukui told reporters recently in Tokyo. "In India, the roads are so congested that it's easier and quicker to navigate the traffic on a two-wheeler," he added. Honda and Toyota are leading the way on cleaner gasoline-electric hybrids, and some environmentalists argue getting prices down on these technologies is where efforts should be concentrated. GM expects to launch its plug-in hybrid Chevrolet Volt in 2010. Renault/Nissan are building an electric car for Israel that will be subsidised by the government. CEO Carlos Ghosn has said it will be the most environmentally friendly commercial car. Tata Motors, which is working with a French firm on using compressed air as fuel, has signed up for the Progressive Automotive X Prize, a $10 million competition to build the first mass-producible 42 km/litre energy-equivalent vehicle. Nicholas Stern, author of a landmark 2006 report on the economic costs of global warming, on a visit to Mumbai this year said, "A lot of technologies are already sitting on the shelves of manufacturers, but it's been easier to persuade consumers to buy bigger cars rather than greener cars that are more expensive." Steve Howard, chief executive of The Climate Group in Britain cautions against demonising low-cost cars or belittling their importance in emerging economies such as India, despite concerns. "It's easy to look at cheap, mass-produced cars and say,