BMW M5 fans currently have two options to choose from these days, as besides the fantastic standard model, BMW M also offers the more focused 625PS M5 Competition.

Not bad, but what if we told you that a third BMW M5 model was on the way? While there’s nothing official yet, the fact that the automaker is testing an M5 on the Nürburgring Nordschleife is significant. Our photographers spotted a white M5 on the “Green Hell” and at BMW’s M Test Center at the Nürburgring.

Those are serious indications that the carmaker is testing something new for its high-performance sedan. At first sight, the car appears to be a normal M5, but a closer look reveals an interesting detail.

The car features a unique decklid spoiler that features split fins — and no, it’s not from the M Performance parts catalog. The design of the aero element is similar to what we’ve seen on the M3 CS and M4 CS. Obviously, this has us wondering whether BMW is developing an M5 CS.

Another hint supporting the M5 CS hypothesis is the fact that the early prototype features M Carbon Ceramic brakes, which are standard on the M3 CS and M4 CS. Besides the trunk spoiler and ceramic brakes, expect the M5 CS production model to feature more aero parts, exclusive CS wheels, and different exhaust tips.

If the M5 CS materializes, it should offer a small power supplement over the M5 Competition as well as lightweight body panels made of carbon fiber-reinforced plastic (CFRP).

Photo credits: CarPix for Carscoops