The Chinese government has announced that by 2020 passenger vehicles will have to achieve the equivalent of 47.76 mpg.

According to the report by Reuters, this could make life tougher for cash-strapped small domestic brands that are already struggling amid a slowdown of the world's biggest auto market.

The rules, jointly issued by five government bodies including the National Development and Reform Commission, would cut passenger cars' average fuel consumption to 6.9 liters (1.8 gallons) per 100 kilometers (62.1 miles) or 34.5 mpg by 2015, according to Reuters. It will be reduced further to 5.0 liters (1.3 gallons) or 47.76 mpg by 2020.

Experts predict this will mean that the Chinese market will have to introduce more fuel-efficient models and invest in hybrid technologies.

While China's latest passenger car fuel consumption data was not immediately available, according to the latest data available it was 7.8 liters per 100 kilometers in 2009 and 8.2 liters in 2008, Reuters reported. The new rules come at a time when environmental complaints have sparked unrest and even riots in some parts of the country.