The carpet in my 1972 220d was pretty threadbare when I got the car. After comparing prices at various aftermarket suppliers I decided to fabricate the pieces myself. Using the originals to create slightly oversized cardboard templates for each footwell area. I reused the foam pads from the front footwells after carefully separating the pads from the carpet. You may be able to salvage the heel pad from the driver's mat for reuse as well. Be sure to trim the cardboard templates to fit after putting the foam pads down first otherwise the carpet sections will be short of filling the footwells exactly. Modern day commercial loop carpet is durable and very close to the texture of the original.
The pieces that cover the sidewalls of the floorpan, the tunnel behind the console and the two odd shaped pieces that tuck under the rear seat bottom are pretty easy to visually size up before cutting.
I discovered that the difference between carpet designed for indoor use and automotive use is a coating of rubber-like material on the backing. Any carpet installation supply store stocks the substance which comes in quarts and gallons and is used for some seam and other carpet repairs. Be sure to choose the latex version rather than the solvent based. It brushes on easily and a second coat can be added within an hour or two.
The final step before adding the color coordinated binding is to test fit and trim each piece as necessary. I jobbed out the binding to a local trim shop with good results. The final cost was about $400.00 plus my time versus almost $700.00 from aftermarket suppliers. The end result looks good, is durable and easy to keep clean plus it was a very satisfying part of my hands on repair/restoration.

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