So, I have mine for sale, ticks a lot of boxes, it really is an excellent car. I'd ideally keep it but unfortunately my track car as at (arguably beyond) the limits of what I can put on the road and not invite trouble.
I looked at weights and considered getting a towbar for the A4 so I could solve the issue but it'll tow a max braked capacity of 1800kg, the track car is 1250kg and that doesn't leave a lot of wiggle room for trailer weight - so selling.
https://www.ebay.co.uk/itm/334128371309
I can't speak highly enough of this car, I bought it after my D3 S8 and had it nearly 4 years - in fact, I posted about it here:
http://forum.a8parts.co.uk/showthread.php?t=13812
Its just had a new MOT, doesn't need a service for a while and although modified, its tastefully done (IMO), the S5 seats are a huge comfort upgrade.