I have a Thule Velospace twin Bike Carrier to transport 2 x E-bikes to Europe Each Year on a Thule Towbar - fits onto my A6 Avant S-Line fine.
Sit securely on the German roads at 70 -80 mph with no indication they rack will fall off.
It has the facility to lower the bikes while on the Towball to gain access to the Boot.
It has locks on Crossbar Arms and Rack itself so can't be in theory stolen while fitted.
I had the Tow Bar fitted Professionally with an Audi Cam Bus wiring so when set up and light pack wired into the socket, the boot remote won't open remotely with Bike rack on.
I bought this model of Rack as it could carry the 2 bikes weight wise + Lower Facility for Customs etc to search car ( must have a guilty face ) and has the built in lights / number plate to easy to fit.Cross bar securing bars come with the rack so easy to fit plus I bought a single wheel adapter so when empty - rack can be wheeled about back to shed etc.
Video on an A6 Avant
Some photos of Manual which is available on line somewhere.
Tried to upload a YouTube video from on line which shows the Rack being fitted to aA6 Avant - but failed - if you search 'Thule VeloSpace 917' it will come up with a few German ones. www.youtube.ghKxnreGpkM
Thule Wingbar Edge and prorides for me, I leave the wingbars on all the time and have no noise at all from them. I do get a bit of noise when the bikes on but you can only hear it when the window's open.
Wingbars & ProRide 598 for me too.
Haven't transferred them to the Audi yet, but use them on my wife's Superb and also my last car.
They've stood up perfectly to high speeds and also bouncing down some dead bumpy tracks.
On my last car I just left them on all the time. Barely noticed any difference, and means if I wanted to nip out on the bike, only takes a minute to pop the bike on the roof.
Use additional locks though if you leave the car unattended (even for a short length of time).
You can also buy keyed-alike lock barrels for all the Thule gear, so you can match the locks on multiple carriers, and the bars, so you only need one key.
Beware of height barriers and low branches though!!
I also have a 3-bike towbar carrier, but find it a lot more faff and only tend to use it for longer holidays when the roofbox takes up most of the roofspace.
It's an Atera Strada. I tried a Thule carrier first but found the Atera to be lighter and a lot easier to put on. It slides backwards out of the way to give you access to the boot.
I got a used set of genuine Audi rails, they were only £70 and in excellent condition. Along with them I also got the Audi bike carriers. I also got a set of Audi rails for the A3 as again they were cheaper and they are so easy to fit.