Open Preferences and then click the Java preference icon. 

 Select "Advanced" and "Edit list" for exception items.

Add "http://www.bmw-planet.net/" to the list.

Apply and Save

Restart the browser.

Go to www.bmw-planet.net again.

Click the "UK flag" (or any other language you prefer)

Click for instance "X3 E83"

Click the "Click here to load..."

Confirm by selecting "Always allow" (or allow just once if you prefer)

Then acknowledge to "Run" the application

After a short time you'll be presented with the navigation menu.

Attempt to navigate to a section and diagram.

Good luck!