Alert Scooby-Doo and the gang because we have a mystery machine in these spy shots. It's clearly a Bentley Bentayga Speed but with modifications that leave us confused.

Specifically, this is a Bentayga Speed that seems to wear the available Blackline Specification pack that comes with blacked-out elements for the exterior chrome. However, this example doesn't have the black 22-inch five-spoke wheels that are usually part of this package. These have a similar design but a different finish.

Gallery: Bentley Bentayga Black Edition Spy Shots

The mystery gets more interesting at the back. Rather than the standard oval-shaped exhaust, this one has a design that splits the pipes in half to retain a similar look but with four distinct outlets. Also, the strakes in the rear diffuser look thicker on this car than what's available from the factory.

Looking at this Bentayga from the side, we think it looks like the suspension might be a bit lower than what's currently available.

Still, it's not clear what Bentley is testing here. Since the exterior doesn't have any camouflage, we're not expecting any major design changes from this model. One possibility is that we're seeing an updated version of the existing Black package with the new diffuser and exhaust design.

Another prospect is that Bentley has revised software or unseen hardware on this Bentayga. We don't generally see automakers lapping a vehicle around the Nordschliefe for no reason, so there's almost certainly something on this crossover that requires testing on the track.

The Bentayga Speed just received a revised interior and tweaked exterior for the 2021 model. Under the bonnet, there's still the twin-turbo 6.0-litre W12 that's good for 626 bhp (467 kilowatts) and 664 pound-feet (900 newton-metres). Acceleration to 60 miles per hour (96 kilometres per hour) requires 3.9 seconds, and Bentley puts the top speed at 190 mph (306 kph).