Depends on the engine/trans/axle combination, but the top speeds listed by Mercedes are usually drag limited, not redline limited.

For example, my 2.6 will achieve low 130s at close to 6200 in fourth gear. The "redline" on the tach is 6200, but the fuel cutoff is not until 6550 or 6650, and the power curve does not feel like it rolls off much, if at all, above the rated peak at 5800.

Shifting to fifth at top speed drops the revs to about 5000, and it will not pull any higher, but it will hold about 5000 revs in fifth on level ground.

Duke