Ah, fellow rabids...j/k

The swap can be done but there are many negative side effects to using the V12. Using either a 6.0 M119 (DOHC V8) or 6.5 M119 would still fit the current dimensions and provide nearly as much power. (420HP or so for the 6.0, well over 450HP for the 6.5) Though still shy of 7.3 V12 grunt it is still more than what the tires would deal with. Then you would have to change to gearing as the current setup is limited to 165mph (redline limited, not electro 155mph) 500E's had enough of a problem with running hot as-is, with the much longer M120 V12 it would only make things worse. Not to mention you'd rape the near 50/50 weight distribution. Another thing to consider is that you cannot (even at Renntech) fit the electronic 5-speed transmission in the W124 which leaves you to modify the crap out of a 722.3 4-speed or put in a 6-speed manual (available at Renntech). The M120 V12 is pretty much two M104's joined at the crank. If you had a W210 chassis then the V12 is a better fit IMO. So pick up an extremely high mile E320 and send it to Renntech/Brabus with a blank check. The only question is where to mount the NOS bottle...j/k

Jim,
Funny you should recommend finding a 500E and doing 6.0 mods....I recently got a line on a 6.0 Renntech E500 that is actually something that could be purchased. I would just need to sell my 95' C36 to do it. (silver/black, 65K miles, no wreck/hit/all original panels, perfect service, Mobil 1 3500 mile oil changes, excellent condition, etc) If you know anyone who might be interested I'm entertaining the idea of the swap (C36 to get into the E60)

Ah, the possibilities....Lee