Canadian researchers say a program by one of the world's largest cities to switch its vehicles to clean fuel has not significantly improved emission levels.

Researchers at the University of British Columbia say their study of the impact New Delhi's 2003 conversion of 90,000 buses, taxis and auto-rickshaws to the "clean fuel" of compressed natural gas has had can provide guidance for other cities considering such projects, a university release said Tuesday.

Crucially, in New Delhi's 5,000 auto-rickshaws with two-stroke engines -- a widely used form of transportation in both Asia and Africa -- the conversion to natural gas produced only minor reductions in emissions that cause air pollution. The switch actually resulted in an increase in other emissions that negatively impact climate change.

The New Delhi program could have achieved greater emission reductions at a cheaper price by simply upgrading two-stroke models to cleaner, more fuel-efficient, four-stroke engines, the researchers said.

"Our study demonstrates the importance of engine type when adopting clean fuels," lead author and UBC post-doctoral fellow Conor Reynolds said. "Despite switching to CNG, two-stroke engine auto-rickshaws in Delhi still produce similar levels of particulate matter per kilogram of fuel to a diesel bus -- and their climate impacts are worse than before."

As much as one-third of natural gas is not properly burned in two-stroke engines, producing high emissions of methane, a major greenhouse gas that contributes to climate change, the study said.

Several Asian cities have even more two-stroke auto-rickshaws than New Delhi, researchers said, including rapidly industrializing cities in India, Pakistan, Bangladesh, Philippines, Thailand, and Indonesia.

earlier related report
General Motors China sales up 34.4% in February
Shanghai (AFP) March 2, 2011 - General Motors said Wednesday that its sales in China, the world's largest car market, jumped 34.4 percent year-on-year in February to set a new record for the month.

The US auto giant said in a statement that with its Chinese joint ventures it sold 184,498 vehicles in the country last month, although this was well below the all-time monthly high of 268,071 vehicles set in January.

Auto sales are typically slower in February due to China's week-long Lunar New Year holiday.

GM set its previous February record for sales in China last year, when it sold 174,306 vehicles, up 51 percent from the previous year.

China's booming market has become increasingly important to GM as demand weakens in the United States. China, where GM's international operations are now based, overtook the United States as the world's biggest auto market in 2009.

GM and its joint ventures sold a record 452,570 vehicles in China in the first two months of 2011 -- representing a 15 percent increase from the same period last year, the carmaker said.

GM's sales in China last year increased 28.8 percent year-on-year to an annual record of 2.35 million vehicles, outstripping sales in the United States.

Auto sales in China rose more than 32 percent in 2010 to 18.06 million units, according to the semi-official China Association of Automobile Manufacturers (CAAM).

CAAM forecast sales and production would grow at a steadier pace this year, by 10-15 percent, after purchase taxes for small cars rose to 10 percent and Beijing slashed the number of new registrations allowed in the capital.

GM has several joint ventures in China including Shanghai General Motors, a partnership with China's largest auto maker SAIC Motor.