The prototype was caught testing in European alps, more specifically, doing brake tests up and down the mountain. Possibly testing the car when fully laden.
As well as the slightly different front bumper bar that shows a thin long grille unlike any other variant along the bottom fascia, the prototype also has different wheels which look like hub caps.
From the image above we can see that the car might indeed be carrying a heavy load in the back, evident by the drooped rear suspension. This could indicate testing of a new, more heavy-duty variant.
Whether it's just this prototype or not, it appears to be lacking roof rails too which are a standard feature on most Skoda Roomster models. This could indicate this being a sports version, or, a more aerodynamically focused eco variant.
From the rear it appears to have no exhaust pipe, although it could be disguised by the camouflage sheeting. Still, we can also speculate it being an electric vehicle of some sort as well.
What ever it is, we'll bring you more on this car's identity as soon we can.