There will be fewer models at this year’s Shanghai Auto Show, which begins today with media previews and runs until April 29th. That is not just because the Chinese government has cracked down on the use of scantily clad women to promote new cars. The real reason is more troubling. For years, China was the industry’s greatest prize. Its car market is bigger than even America’s—and lately has provided some Western manufacturers with over a third of their global profits. Alas, after years of double-digit increases, sales growth looks likely to slip to 8% in 2015. Margins are being squeezed too, both because consumers are less willing to pay hefty premiums for foreign brands and because regulators are using competition laws to push prices down. Worse, car firms keep spending billions on new factories despite a huge overhang of unused capacity. Carmakers in China may be heading for a crash.