We were not quite expecting this.
The next generation BMW 5 Series itself hasn't even launched yet, but the automaker is already testing a new M5 on the streets of Munich. Our spy photographers just managed to capture these images of an early M5 prototype, and they could observe this wasn't just a regular 5 Series because of two things: quad exhaust pipes and the sound it made. But there's something else we've spotted here that'll please some and annoy others: an extra "fuel cap" on the left front fender for what's likely a charging socket.
Yes, that means this M5 test mule could be a plug-in hybrid. Now, our sources claim that all previous 5 Series prototypes caught testing also featured that fuel cap, so it could be just for show and have no functionality at all, or the next M5 could offer plug-in hybrid tech. What we do know is that BMW will make all-wheel-drive available for the first time on the new M5, something purists likely won't want, but is needed because of fresh competition from Audi and Mercedes-AMG. We're willing to bet a possible plug-in M5 really won't sit well with them either.