If it was uncomfortable vehicle costing as much as it did, id be selling as soon as i could and buy something that didn't annoy or hurt me as soon as i drove it.
Funny enough a friend of mine had a 211 facelift Sport e280 cdi, It didn't have nappa leather just the usual sport trim seats and they played my back up after 50 miles.
My Pre facelift e320 cdi Avantgarde with nappa was comfortable over 660miles across Europe no complaints at all.
I certainly couldn't live with a Uncomfortable car no matter what it was. Obviously only the Op can tell us how he feels.
Ok, this is the pedal arrangement for my 911- I've driven this car to the Alps and it was the perfect companion for the journey, I jumped out feeling great.
This is my right leg in its "natural straight-ahead" position, it puts my foot directly over the throttle:
This is the E63:
And here is the same picture, but with my right leg present in it's natural straight-ahead position:
I've got two sets of E63 brake and accelerator pedals coming (ordered from eBay) to cut up and experiment on.
The hard part is going to be moving the brake pedal over to the left, I imagine that the route forward is going to be to cut the lever arm, weld it onto a section of tube, weld the lower part onto the other side of the tube to the left of it's current position, then go mad with the gussets (nudge nudge).
The accelerator looks to be bolted into the chassis with two M10 fasteners, I would hope that a plate could be made that attaches to the chassis points currently occupied by said fasteners, and the plate replicates the mounting points 100mm (or whatever it turns out to be) to the left.
I'm happy to close up the distance between the two pedals, but there's no getting away from the fact that the brake pedal needs to move a fair way.