mercedes dealers would install the block heater free of charge during the first year of ownership. They included a coupon in the owners manual.
Those who live in cold climates mught have tken advantage of it. In california I have never seen a block heater on a benz. Depends on where you live. $300 seems like a bunch.

henry

__________________
63 190d (sold)
69 220D (sold)
69 280SL (sold)
76 BMW 2002 (sold)
86 190E-16v (Demised at Laguna Seca Turn 9)
87 300SDL (sold)
87 300SDL 135k
87 300TD 280k (sold)
95 E320W 311k
95 E320w 180k
05 C320 4matic
06 E320 CDI 90k (Totaled by a texting 19 year old girl in a nissan)
2013 GLK 250 Bluetek 4MATIC 295k