BMW showed off its new 4 Series coupe in concept form at the 2013 Detroit Auto Show earlier this year, but it won't be long before we see the production model, evidenced by this modestly camouflaged prototype spotted testing. In case you forgot, the 4 Series serves as the replacement for the two-door versions of the BMW 3 Series, just as the upcoming 2 Series will effectively be the new version of the 1 Series coupe and convertible sold in our market.
The spy shots you see above are not of a BMW 3 Series Coupe. Of course, that's just because the German automaker has apparently decided that coupes and convertibles deserve their own numerical distinction, one step higher than their sedan siblings.
As we all look forward to the F30 2012 BMW 3 Series spawning its forthcoming coupe bodystyle as well as a new M3, today's treat is a bit of both. Our spy shooters caught this car testing in Europe, which is clearly an M version of the 3 Series coupe.