Does my R320 have a block heater?
 

I don't see any mention of one in the owner's manual... is there one already installed or is there a dealer option/accessory?
I don't have any problem starting, but I was looking for a quicker defroster action in freezing weather... thanks for any info, Bob

No, block heaters are not installed on these diesels. The pizeo injectors do such a good job of injecting very small quantities of very finely atomized fuel, no block heaters are necessary or required. Not even the heat of 20:1 compression is necessary, the engine is designed at 16.5:1 and cold starts just fine.

My R320 started at 8 deg F recently with only a few seconds of pre-glow.
Amazing compared to my previous 300D which wouldn't start at all below 22 deg F, and my 1984 300SD which would crank for 25 seconds after a full minute of preglow at 8 deg F, but would start with no block heater :)

What I was looking for was faster defrosting when there's ice on the windshield, preferably by heating the coolant via an OEM block heater in one of the freezout plug positions or and/or a conductive heater on the oil pan aftermarket option.