Maserati appears to be working on a facelift for the Quattroporte. The car has been on the market since 2004 and we spied this prototype in Germany as it tested on, and around the Nürburgring race circuit.The changes appear to be focused on the front fascia with a small alteration to the rear bumper. The camouflage suggests that in addition to changes to the front bumper air-intakes, Maserati stylists may have made some changes to the Maserati’s overall grille shape, and to the headlights. The rear end will stay the same. The changes amount to the normal mid-cycle facelift, which should go public late this year, perhaps at either the LA or Detroit auto shows.