Car owners in Beijing have multiplied since 1992, creating a congested, choking city and a class struggle between the haves and have-nots. The capital has been outlawing various small cars and vans from main roads and especially targeting the small, yellow taxis which once ruled the streets. Senior officials recently helped cast dozens of these vehicles into a furnace at the Capital Iron and Steel Works (Shougang), a huge source of air pollution. Drivers are up in arms at stringent annual examinations which start this year, part of efforts to clean up car emissions. Beijing already has compulsory lead-free petrol and emission standards are being raised.