That was one thing I thought of Jon when I posted about the fire damaged e-bay Mercedes cars a while back. The damage looks very close to the firewall. Very good chance that all of the wiring under the dash board is ruined. Even if the wires under the dash panel are not destroyed, I am sure that the wires under the hood that ran inside the dash are burned and will need replaced. All you can do aside from rewiring the car under the dash, is to splice in new wires and I think that would be very unreliable, with such a complex electrical system. Also, as I mentioned before, from the photos, it looks like a bundle of burned and jumbled wiring as far front as the right front fenderwell area. Do not know what that could be. A trend I noticed- it looks like these 90s to 2000 Mercedes with fire damage- the fires look to be starting at the right front firewall area on all of these cars.
There is a 93 S500 4dr on e-bay, with rear end fire damage. Inside was saved and not damaged, nor was the engine. Interior would need a good cleaning. Probably a lot cheaper to repair the 4dr S500. Good luck.
1993 Mercedes 400SEL 4dr
2012 Honda Civic LX 4dr
1972 Chevrolet Caprice Kingswood Estate 9-passenger wagon
1973 Pontiac Grand Ville 4-dr hardtop sedan
1988 Mercedes 300SEL (was mine, now mothers)