if its an Alpina car there should be a black plaque that says Alpina, the model and the number of the car because they build them in order. I've seen it located in the roof just in front of the rear view mirror on some cars.
His--2000 BMW ///M5 .:Jet Black on Black:. Individual - Style 65 Wheels; 9.5" Square Set up;275 Tires;10mm/3mm Spacers; Black Kidneys;Muffler Delete; 3.5" Dual Tips; Beast Power Sway Brackets; "Dinan" Ducts; E60 SSK; BC Coils
Hers--2000 BMW ///M5 .:Avus Blue on Grey/Black:. '01 Exterior Upgrades; E60 SSK