Dinan makes a fixed plate for the non-m Z4. They are, however, quite expensive for what they are (~$325+). At that price the Ground Control plates are about ~$50 more and the Vorshlag plates are ~$125 more. From my understanding, the GC plates are more daily friendly and the Vorshlag are more intended for autocross and track.
Links:
https://groundcontrolstore.com/colle...ter-plate-pair
https://vorshlag-store.com/collectio...plates-perches