For years, there have been rumors that BMW is plotting a new flagship SUV called either the X8 or XM that will slot above the already-massive X7. Since then, BMW has been caught testing numerous prototypes of the X8 with unique design cues not seen on any other BMW model. In our latest prototype sighting, the X8 is sporting a very unusual exhaust layout featuring two pairs of stacked exhaust pipes that makes the rear of the supersized SUV look very aggressive.

The stacked exhausts were covered up on previous prototypes and certainly help the X8 stand out in BMW's model lineup while hinting at its performance.

This isn't the only unique design feature either, as the prototype has unique split headlights positioned lower than the X7's. We can already tell the X8 is going to have a polarizing design, but BMW is no stranger to controversy when it comes to styling. In terms of proportions, the X8 will be even longer than the X7, which measures 203.3 inches long, allowing for more rear legroom in the luxurious cabin - especially if the X8 is only offered with up to five seats.

The "Hybrid Test Vehicle" sticker on the rear indicates this prototype has an electrified powertrain. This could be the entry-level BMW X8 M45e, which is expected to use a similar plug-in hybrid drivetrain as the BMW 745e.

The 745e utilizes a 3.0-liter turbocharged inline-six and an electric motor producing 389 hp and 443 lb-ft of torque, while a 12-kWh battery provides an electric driving range of 16 miles, but the X8 will have more power and range.

Allegedly, the range-topping X8 M will be powered by an electrified 4.4-liter V8 producing 750 horsepower, making it the most powerful production BMW ever. The standard BMW X8 is expected to break cover later this year and compete with the Audi Q8, followed by the more powerful M variant next year. Hopefully, it won't be long until the prototypes start shedding some camouflage to give us a clearer look at the luxury SUV's peculiar design.