The 2010 model year facelift for the Mercedes Benz S-Class was just revealed back at April’s New York Auto Show, bearing a slightly revised face and an updated powertrain lineup. Today our spy photographers have captured images of a stretched-wheelbase limousine variant in testing.

Clearly sporting the new 2010 S-Class face, the limo spied is still in the earlier stages of testing, judging by the mismatched character line along the side of the car.

Little is thus far known about the car, but it can be expected to use the same running gear found throughout the rest of the new S-Class lineup, though likely only paired with the larger engines. Probable candidates include the upper-end V8 petrol engines and the range-topping diesel V8 generating up to 354hp (264kW), found in the S550. Expect a V12 model as well.

While the facelifted S-Class range officially goes on sale this month, this stretched limo version isn’t expected to go on sale until early next year.