Twin spark ignition
 

I need a definitive answer to settle an arguement: starting when and in what engines did (does) Mercedes utilize twin spark plug ignition systems? I've seen twin spark plugs used in the current V-sixes, eights and twelves but I understand the eights and twelves did not have this type ignition when the V-six was introduced.

I believe the twin spark plug and three valves per cylinder design started in 1998 when MB released the M112 and M113 engines.

The E430 was the first V-8 with dual plug heads M113 and it didn't come out until January 1998. All of the V-6 engines came out in July & August 1997.
The W140 chassis never used the M112 & M113 engines, the SL500 didn't get that engine until 6/98.