CHINA has lots of people, not much oil and rulers who love big projects. Small wonder that makers of electric cars see it as the market of the future. The Chinese government wants to have 500,000 electric cars, lorries and buses on Chinese roads by 2015 and 5m by 2020. It is providing customers with subsidies worth up to 60,000 yuan ($9,250) and other incentives, too. If it carries on doing so, electric cars and plug-in hybrids could account for 7% of new-car sales in China by 2020, says a forthcoming report by the Boston Consulting Group. That would make China the biggest market for electric vehicles, by volume, in the world.

Foreign firms are salivating. But they are also nervous. “The price for market access has gone up,” says Michael Dunne, the president of Dunne & Co, a car consultancy in Hong Kong. Foreign producers are being told about new “draft” rules which mean they must share more intellectual property and branding rights with their Chinese joint-venture partners, he says.

On June 27th Carlos Ghosn, the boss of Nissan—which with its partner Renault is taking the biggest electric-car bet by launching a range of plug-in models—said he would wait to learn more about the new policy before deciding how many electric cars Nissan will make in China (including the new Nissan Leaf). “We will adapt our strategy to the rules,” he added. At present there are plenty of unknowns, such as whether subsidies will benefit only Chinese brands.

The local champion is BYD, a battery-maker turned car producer in which Warren Buffett has a stake. BYD is struggling, however, to get its new e6 electric car to market. It was supposed to go on sale in America last year, but was not ready. It is now being tested by taxi fleets in Shenzhen, where BYD is based.

The Chinese government could juice up the market by insisting that more taxis and government vehicles switch to electric. But persuading Chinese consumers may be harder. Electric carmakers typically claim that their vehicles can travel a long way without recharging, but that range can fall by a third or more if you turn on the air-conditioning, accelerate hard or otherwise drive normally. BYD claims that the e6 has a range of 300km (186 miles), which is about twice that of Nissan's Leaf. Motoring hacks have yet to put that claim to a good road test.