I recently looked at seats from a 2013 C250 MB Coupe, they closely matched the outline of the E Body seat but offered good lateral support, the local wreckers wanted $1000 for a pair, dropped that idea pretty quickly. So because I like the shape/outline of the E Body seats and to avoid having to have an engineering certificate done (its an Aussie BS thing) because Ive changed the seats, Im looking at buying a set of front seat covers and the seam that runs down either side of the base and back, have an upholsterer insert a piece or pieces to create an area for hard foam to build the lateral support for a more modern looking seat. As i need to re-foam the seat due to it breaking down they can add the support to the new foam base and back, should look as it was meant to be there.