Preventing the next Dieselgate: EU can now oversee, overrule new-car approval by member countries

Portable Emissions Measurement Systems (PEMS) on a Peugeot 308With the exception of California's longstanding ability to set its own tougher emission standards, any car legal to sell in one state of the U.S. is legal to sell in all of them. And aside from a handful of differences—daytime running lights, speedometers marked in km/h—Canadian-market vehicles are largely the same as well. Within the...