The changes that are easiest to see, and that make the biggest differences, are in the headlights and grille. On the current E-Class, the inner edges of the headlights are roughly vertical, but on this new model, they lean in toward the grille. This is a more aggressive look, and one pulled right from the CLS- and A-Class models. The grille is also reshaped to accommodate the new lights. The outer edges also lean in toward the center.
The rest of the front fascia on this E-Class is well-covered, so it's hard to make out any other specific changes, but it looks as though the bumper and lower grilles will be updated. The rest of the car is completely uncovered, and it appears to be identical to the current E-Class wagon. There is a possibility of some detail changes that haven't been implemented on this prototype yet.
Powertrains will probably be carryover from the current model. That will include the base turbo four-cylinder, twin-turbo V6, AMG twin-turbo straight-six and the AMG twin-turbo V8 models. There's a chance that the V6 could be replaced with the CLS 450's straight-six, a detuned version of the E 53 six, but we'll have to wait and see. We'll probably see the reveal of the facelifted model sometime next year.