Platinums and NGK's might be fine for a 320i, but not for a Big Six. You want the silver Bosch plugs (Silber is german for silver). These plugs were specifically designed just for the 6er. It's something about they way they spark and the way they adjust to the heat. Silver is definitely what you want. So special order em! Beru plugs have silver in them and might work well too.