The sedan M was launched as a 2003 model car by Infiniti in order to widen its offerings and fill the void between the G and Q sedans.  The design of the first generation of M (2003-2005) was only scarcely appreciated and not successful commercially.  Perhaps Infiniti was struggling with the product definition and positioning for the M.  The second generation (2006-) finds its footing, thanks in part to a design which is applauded as much more successful.  It positions itself as an alternative to the Acura TL, Audi A6, BMW 5 Series, Lexus GS and Mercedes E-Class.  Note that the M is the flagship of the Infiniti sedans since 2007 when the Q (2002-2006) ceased to be produced.