I remember reading your previous posting on the 190's clutch slipping.
I think what you are trying to determine is whether by using the car for "after maybe 1 hour driving in heat" that the clutch is in fact slipping, slightly.
What is the free play on the clutch pedal/linkage when cold verses after one hour of driving?
I also have the Haynes manual with its sections on the clutch. It is multi-paged, but I will try and see if there are any specific clutch related descriptions that could match what your are experiencing.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)