Shanghai-based Buick dealer Ron Li in late April found himself in an unfamiliar quandary: how to sell off almost 80 sedans and SUVs crowding his dealership lot.

The crux of the problem: a June 30 deadline for cars built to so-called China-5 emissions standards to be sold. After that only vehicles meeting new standards could be put up for sale.

People were still coming in but weren't buying the stage-5 cars, Li said.