My dad drives an '06 CDI and says he gets better fuel mileage in Comfort mode as well and he finds it more comfortable.

I haven't noticed a big difference in shifting all that much between C and S though, whenever I drive his car.

Fun fact: For the longest time we assumed S stood for "Sport". We couldn't figure out what C meant though, until finally someone decided to leaf through the user manual. We all had an: "oooooohhhhhhh, that's what it means" moment...

Apparently C is supposed to take off in second gear, so it should be more comfortable in stop&go traffic.

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"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)