Mine is not an all road and has s-line lowered ride so the handling will be totally different but it takes a slippery road and a heavy foot to invoke any vagueness in the handling of my A6 C7. I appreciate that air suspension with a higher ride will feel different to mine so what I would suggest is you find a similar A6 for sale and ask for a test drive on the premise of purchase - if it is as bad as yours you know that yours is as good as it gets or you have found a brace of bad ones. The last car that has steering that unnerved me was a 1972 land rover - now that was vague especially when towing.