Coupé comes from the French word for 'cut', indicating that the vehicle seating is close-coupled. That usually implies two doors, but it always means a smaller rear seat volume. That translates as less rear leg room, and less headroom, the latter resulting in a sportier exterior roof line.

That, and the fact that when you invent a marketing label such as SAC you get to call yourself the market leader for a year or so.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue