On the 722.4 transmission, there is a "cold-shift relay." Mercedes engineers were very clever; to warm up the catalytic converter faster, in order to drastically reduce emissions, the transmission holds 2nd gear until either the coolant temperature has reached 50d or the engine is revved above 3100 RPM.
There you have it in a nutshell!
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)