They aren't wearing much camouflage but have some concealment panels on the body.

A new spy video catches the Mercedes-AMG E63 sedan and wagon during their development at the Nürburgring and the roads nearby the famous track. Both of them wear light camouflage that only hides the tweaks at the front and rear.

The E63 should wear Mercedes-AMG's Panamericana grille with vertical slats, but it's not on either of these vehicles. The sedan has Mercedes' crossbar design, and the wagon wears an egg-crate-style covering. 

The sedan provides a better view of the front fascia with large openings for directing air to the radiators. The wagon test mule has a cover over this section, but the multiple holes in the piece still allow for airflow.

At the back, the wagon wears a little less camouflage, and it only covers the general area around the taillights. It suggests that there might be new lamps and no other changes. The sedan has more considerable camouflage, but the material still appears only to be there for hiding the rear illumination.

Like the current E63 expect the refreshed models to use Mercedes-AMG's twin-turbo 4.0-liter V8 engine. It makes 603 horsepower (450 kilowatts) in the existing S models, but AMG pushes the output to 630 hp (470 kW) for the GT 63 S Four-Door Coupe. This indicates that there's room for the power to grow. A series of trademark filings hint that a more powerful variant could also be on the way by adding hybrid assistance and possibly takings the specs to around 800 hp (597 kW). 

Look for the updated E63 to go on sale in 2020. The timing for the debut isn't year clear, though. It's entirely possible that we could see an unveiling before the end of the year.

Source: Automotive Mike via YouTube