A couple of changes to this. First, for EK metal reward flights booked with QFF points, emphasis underlined:
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Emirates has made some changes to its Chauffeur Drive policy and we wanted to update you before your upcoming flight.
From
1 March 2019, Qantas Frequent Flyers booked on a
Classic Flight Reward ticket in First or Business for a flight operated by Emirates will no longer be eligible for the Chauffeur Drive service.
There are no changes to Classic Flight Reward bookings on Qantas services. Qantas Frequent Flyers with a Classic Flight Reward booking will continue to be able to book Chauffeur Drive on eligible Qantas services.
If you’ve already booked a Chauffeur Drive for your upcoming Emirates flight
Qantas will honour all existing Chauffeur Drive bookings with Emirates made on or before
1 March 2019 for travel on an Emirates operated flight up until
1 March 2020.
If you have not booked your Chauffeur Drive service and are travelling on an Emirates flight before 1 March 2020, you can still book your complimentary Chauffeur Drive before 1 March 2019 through Manage Your Booking.
If you have any questions, visit qantas.com/chauffeurdrive or contact us here.
Best regards,
Qantas Frequent Flyer team
Probably in line with this:
Emirates to axe chauffeur drive on award tickets
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Looking here for QF metal :
Chauffeur drive | Qantas AU
Changes to the Chauffeur Drive program
Effective 1 March 2019, Qantas' complimentary Chauffeur Drive service will
no longer be offered on Qantas operated flights in Auckland, Christchurch, Wellington and Singapore, and the complimentary mileage band for London is amended from 70 miles to 50 miles.
I don't know if this was allowed before, but it looks like you should be able to book CD at MEL and PER if part of a domestic only QF9/10 itinerary. ie. it does not say you cannot.
Chauffeur drive terms and conditions | Qantas AU