Does anyone know why my MPG gauge goes crazy when I just barely step on the gas and almost immediately goes back when I let off. It seems "loose" and unaccurate. NO ONE has found out the reason why yet. Not even the dealer.

BTW its an S500 coupe (W140). Thanks in advance everyone

They are not a good indicator, I think it is more of a vacum gauge, at cruising or constant speed it might indicate MPG