Rev counter has stopped working (any ideas anyone??)
Always use a specialist for tuning & servicing... Mercedes dealers don't have a clue how to "deal" with a Cossy!!!
The specialist I use says that this switchable auto model is quicker than any of the manual models he works on.
Fit 17" wheels with 40 profile tyres to really sharpen up the handling.
Re. rev counter not working.
I had the same problem, after wasting hours trying to fix it by dismantling the clocks, it turned out to be a fractured fuse!
Good luck
Dave.