I remove my rear seats all the time and I haven't seen anything.
If you really want to know, go to the dealership with the VIN.
You can try the other obvious hints, if you have sport seats, a steering wheel with M coloured stitching, and 16" stock wheels (or a 16" spare aluminium wheel)
There is only like 0.59" difference in suspension height, and sport and non sport struts are pretty much interchangable.
"Driving is like a narcotic, an addiction that can take over lives. It ruins people, breaks families apart, and even kills. Itís habit that needs to be fueled. Time, money, rationality, sweat, knuckle skin, and anyone who disapproves are of little importance to a driver, and are often overlooked. Hi, Iím Nelson, and Iím a drivaholic."