A mystery prototype wearing the body of a Mercedes-Benz SLS Electric Drive has been spied around the Nurburgring in Germany, raising questions as to what the company is developing.

The SLS Electric Drive was an all-electric version of the SLS AMG supercar, featuring combined outputs of 552kW and 1000Nm from its four electric motors.

However, this example is wearing more scaffolding than the average construction site, and also has some odd equipment stuck on the wheels - we're not exactly sure why, though.

One possibility is that Mercedes-AMG is preparing an all-electric version of the current GT, though the bits and bobs stuck to the body could also point to early versions of autonomous driving systems.

It's not as if the company is trying to go unnoticed either - the SLS mule's bright yellow paint and stuck-on equipment is hard to miss.

For now, we'll have to wait and see. Click the photos tab for more images.

What do you think Mercedes-AMG is working on with this SLS mule?