Business Green: Motorists in Shanghai are set to get a one-time subsidy of up to 20 per cent of the retail price on eco-friendly cars under a scheme launched by officials in the Chinese city. The incentives, to be offered in 2010 and 2011, will offer a maximum subsidy of $2,923 for the purchase of a hybrid, all-electric or fuel cell passenger vehicle. Drivers of fuel-efficient cars will also be offered incentives, including a break on some road taxes and access to more streamlined auto registration …