Ha I say the same thing about my 7-speed 722.9 equipped cars. When I had to drive my son's E300D back to Clemson I forgot how high that thing revs on the highway (ca. 2500/min for 70 mph) and how loud it was (even with all the skirts and covers on).

The OM642/722.9 combo runs at about 1800/min at 70 mph and is practically silent on the highway.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech