Easy
In chronological order for diagnostics of clutch slurring.
1. Do the 50miles/h plus both paddle pull back to reset the wheel speed sensor as per owners manual.
2. Put in sport mode, warm up car and do a few redline pulls in each gear, then off sport mode and do medium load gear changes ... lastly put it in slow shift and do some carpark plodding around type gear changes so the system can learn and re-adapt. Repeat a couple of times and see if it improves. If not move on.
3. Check diagnostics clutch condition as per this thread:
http://www.cslregister.com/forum/showthread.php?t=6164
4. If all above fails, jack up car and check the linkage collar between the shift actuator and gearbox isn't rusted and seized (part 9 in diagram below) Part numbers : 25112229793 (gearshift rod collar) 23411466134 (dwell pin) 25111222451 (dwell pin locking ring) - this can cause slurring type feel as the gear becomes difficult to engage and you experience delays (thus clutch slur)
5. Next hook the car up to a diagnostic laptop (I recommend GT1 here and NOT INPA - I have had plenty of adaptation reset experience using various tools available (I own all but one in the list) - from GT1, INPA, ISTA, Autoenginuity, Autoland, Autologic ect - I can tell you for a fact that the GT1 does the adaptation the best. The reason I believe is because the GT1 was designed for our cars made during our periods. INPA has an automatic reset function which I have used a couple of times on a couple of different cars and each and every time the results have been anything but good (I believe it is the way that the software is run that causes this) - in fact once it messed up a car so badly that I had to redo the adaptation three times using the GT1 before it came right - anyways, I recommend GT1 only for clutch re-adaptation)
Short form (in correct order):
- Carry out Clutch value teach in
- carry out clutch slip teach in
- reset clutch curve
long form (in correct order):
- Adapt Transmission fully
- teach in clutch value
- clutch slip teach in
- reset longitudinal acceleration sensor
- reset clutch curve
6. If all above still don't solve the issue - I would reprogram the DME with the latest 0401 software and update the SMG control module to the latest software version.
7. If the above still doesn't resolve the issues then its time to drop the transmission and check the clutch in physical form, in particularly the following parts:
- pressure plate (Self Adjusting pressure plates can play up)
- crappy clutch release bearing wear (uneven wear? less likely but possible)
- Guide bush (part 1) below - this is common for it to wear unevenly causing it to catch on clutch engagement. Mine was replaced at low km due to uneven wear on this guide
7. If the above still don't resolve the issues, then I would start to look elsewhere on ancillary items such as the clutch slave actuator, SMG pump ect ... but that's probably getting too far removed from the original poster's question and warranty another write up.
Hope that helps.