Mysterious Ford Fiesta spied, is it the Fiesta RS or a mule for the next-generation model?

A mysterious Ford Fiesta prototype has been spied undergoing testing in Southern Europe.

While a number of publications are claiming this is a prototype for the Fiesta RS, our spies believe it is actually a mule for the next-generation model.  It's hard to prove one way or the other but the current model is getting a little long-in-tooth and our spy points out the numerous changes seems to indicate this is a mule instead of prototype for a high-performance variant.

However, the fact that the car is testing alongside the Focus RS has raised a few eyebrows.  This doesn't necessarily mean anything but Ford Performance manager Tyrone Johnson has previously said "There’s more to come from the current Fiesta" including a high-performance variant.