I didn't think the 300E had a knock sensor ??? I know when it's close to 100 degrees outside, if I run 87 octane in my 91 300E I will hear pinging. I have to use 89 or 93 (premium).

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280