Why is it some c7 rs6's can be used for towing and some can't..seems to be early models can

You can only tow if you got air suspension. You can’t tow with DRC

Yes that's correct I've found out the hard way by not checking..I towed with a 2013 model with adaptive air suspension and naturally thought the newer one with drc would be the same but I was wrong...any how I removed the cylinders to fit the bar and repositioned them under it to get me away this last few months but its time now to take the bar off and sell the car and buy one that Is type approved for towing..I went through dvsa..vca and even audi to see if there was a way round it but there isn't..so do your checks first and don't get caught out like I did