My BMW owners manual (E 30) says never overfill the gas tank
cuz it may affect some emission components.On 2-3 rare
occasions, I did overfilled my MB.Is there any harm done?

Not a problem if it happens only once in a while. The following is a reproduction of a simple explanation.

"Your emission control system actualy consists of several sub-systems, one of which is designed to prevent raw gasoline vapors from being released into the atmosphere. It does this by trapping the vapors in a charcoal-filled canister so they can be drawn into the engine and burned later when the engine is running. If you continue filling the tank beyond the normal "click-off" point you can overload the system with vapors. This can cause the engine to run "too rich" and could eventually ruin the charcoal canister."

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Reno

'93 300E 4Matic
'98 Nissan Altima
'00 Yamaha Road Star Silverado

And you will get slobber marks on your 1/4 panel which looks disgusting.

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95 SL500 Smoke Silver, Parchment 64K
07 E350 4matic Station Wagon White 34K
02 E320 4Matic Silver/grey 80K
05 F150 Silver 44K

ALMOST all 1998 & later MB's have OBVR (on-board vapor recovery) systems & if you try to keep filling after the nozzle clicks you CAN & will do damage to that system. ALSO you might get a fuel bath when removing the nozzle! HAVE seen several collasped fuel tanks from this! Don't overfill these models!!

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Retired Moderator

Thanks Doc.I've seen a of lot people
overfill their gas tank esp.when gas
prices goes down.