Look up the last 7 digits of your VIN (from your service book) or by putting your details in here : https://www.bmw-warranty.co.uk/Login/Index
Once you have the last 7 digits of your VIN enter them in a VIN decoder site like this one: http://www.bmwvin.com/?vin=LJ50370&confirm_code=bqgxh
Wala