Here is a list of options that were available on the 2005 CDI here in the US:

Used 2005 Mercedes-Benz E-Class E320 CDI Sedan Options, Packages & Configurations - Motor Trend Magazine


This is the folding rear seats option:

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Rear Seat Package - $540
Asymmetrical split bench front facing rear seats; Rear seat center armrest with ski bag
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I don't have a picture but there are two pull handles/buttons under each of the rear seats that allow them to lift and pivot forward against the backs of the front seats. There are two handles in the top of the trunk that release the split rear seat backs which can then be folded forward. I think the head rests fold back into their stowed position under the rear window.

My experience is that there are not many CDIs that had this option. I think MB later incorporated the option in E class vehicles.

There were lots of options available. I really like:

Sunroof, Nappa Leather, Drive Dynamic Seats, Heated Seats, Fold down rear seat, Active Bi-Xenon headlights, and trunk closer (just cool).

There are also a few options I think would be nice but do not have first hand experience with: heated steering wheel, Sirius Radio, Voice Telephone (blue tooth??), Pano Sunroof, air cooled seats.

Keep in mind, though, that some options do have high failure rate and can be very expensive to repair: keyless go, Bi-Xenon, Pano roof

__________________
-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991