Mercedes engineers have been busy testing several new prototypes at Colorado's Mt. Evans roadway, with both the upcoming C63 wagon and the facelifted SL roadster spotted on the high-altitude pass. These shots were taken by Doug DeMuro who you may remember also sent in the pics of Ralph Lauren's all-black Bugatti Veyron driving near the designer's ranch near Ridgway in Colorado.

Mercedes took the wraps off the new C63 sedan at the start of this month, and the forthcoming wagon variant is in line to get the same performance upgrades. This means the new sports wagon will be powered by a 457hp hand-built 6.2L AMG V8 developing peak torque of 600Nm. The spy shots reveal the new C63's bonnet power bulge, pumped wheel arches and the front bumper side vents. Previous versions of the AMG prepped C-wagon were never sold in the US, but the fact that Mercedes engineers are testing it in Colorado means we might see it Stateside.

Another new model spotted on Mt. Evans that same day was the facelifted SL roadster, which is likely to feature a new SL63 variant as well. The prototype reveals a new front-end design for the SL with different shaped headlights, plus a new bumper and grille, but we'll have to wait until it's launched next year to see how it all pans out.

Big props to Doug for sending these in!