relinuca

My '09 E350 4Matic has a 5-speed transmission whereas the non-4Matics have a 7-speed (or is it a 6-speed?). Anyway, I'm curious as to why M-B changed the # of gears for the 4Matic. I've gotten various guesses from dealership folks on this.

Comments?

relinuca

1985mb

Correct, it's a 7-speed automatic on the RWD cars (not a 6-speed).

I don't believe it's a question of MB "changing" anything on the 4Matics--if anything, the 4matic drivetrain "kept" the original transmission, the 5-speed AT, dating back to the W211's debut in 2003.

Over the W211's life cycle, the RWD versions of the E550 and E350 were introduced to the 7G AT. The 4matic cars did not get 7G until the W212 model change.

Why? I am not entirely sure. MB was either unfinished on the R&D of the 7G/AWD combination and/or wanted to spread out/reduce the cost of R&D'ing it by skipping the W211 generation. If the ROW 211 cars got 7G 4matics, then the answer lies in something unique to the NAm or US market (see below).

Federalization is a big expense for any importer, and apparently each combination of engine/drivetrain/transmission is considered a 'unique' vehicle. Having already certified the 5AT 4matics, MB did not want to spend additional dollars on re-certifying the E3504m and E5504m with the 7G.

mkhurley

Considering the RWD AMG's still used the 5sp also, I'd venture to say it's probably something to do with the load on the trans.

relinuca

To 1985mb...certainly your explanation is the most rational one I have been offered. And BTW, the 5-speed performs just fine, especially when left in the Sport mode.

4Matics have a "bump-out" quite noticeable in the front footwell/passenger side, undoubtedly attributable to the front drive transfer case being side-mounted to the transmission. I had theorized that the "loss" of two speeds for the 4Matics might have been necessitated by the integration of the front drive shaft, etc.

relinuca

Barry45RPM

With the FWD Transfer case and other equipment, there wasn't room for the new (at that time) 7 speed in AWD cars. The 5 speed was the transmission for all of the 211's built in '03. It was introduced for '04 where it would fit. Your center trans tunnel where it meets the passenger door is different from RWD cars too.

PS Yours is a smother down-shifting transmission too.

1985mb

So it seems like they skipped engineering the 7G into the W211 AWD chassis--I'm sure plans for the W212 were already underway and it was probably deemed more economical to integrate it into the new platform "from scratch"