Not that these statements will help BMW avoid scrutiny. The European Commission's antitrust regulators are already investigating the claims, and politicians in BMW's home country are calling for transparency. The Bavarian brand isn't facing any formal accusations, but it's clear that officials view the report as credible enough to warrant a closer look.

Whether or not BMW is in hot water, the allegations reflect a rapidly growing effort to scrutinize diesel emissions among car makers around the world. Regulators are worried that numerous companies cheat on emissions tests for the sake of their bottom line, and that they're hurting the environment to the point where they shorten lives. Recent efforts by BMW, VW and others to embrace electric cars may be as much about moving past diesel's controversies as they are preparing for the future.