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1.
MBSMPG is an acronym for Manufacturer's BullShit Miles Per Gallon. It is the obviously bullshit-laden number that car manufacturers like to advertise along with their cars.

The method of calculating this number varies from manufacturer to manufacturer, but the general formula is very simple.
MPG + 20% = MBSMPG
Television Commercial: "The Joyota Marolla gets up to an impressive 300,000 MPG! You'll never have to fill your car up again!"
Jack: "I think he meant to say MBSMPG"
Pablo: "No habla engles."
by PabloIsActualDolan March 06, 2013