HI, I saw your post on your 2018 A4 with coolant leak. I too have the same problem with my 2017 A4 Allroad. There is a distinct odor of coolant upon exiting the vehicle. I've had Audi look at it 5 times Pressure test and was always told. " We can't find a leak" "We can't smell anything"
I have 37K miles on it and the coolant has run low three times. Did you ever get a resolution to your coolant leak? I filed a complaint with NHTSA (National Highway Traffic Safety Administration).
Looks like there are few others who have filed complaint with them also. Audi offered me a 1 yr extended warranty but I have not accepted yet. Just doing research now and considering next steps.

Hi Jeff, thanks for the note. Short answer is that I don't think I got it resolved to satisfaction. I've had new tires put on, balanced by 2 different dealers and 3 times by Discount Tire. Discount tire made the biggest improvement, but at this point I am still tinkering to make it better (re-torqing lugs, moving wheels around, etc). All balances were 'road force'. When I brought it to the 2nd dealer, I am not sure how much digging they did and said the wheels were out of balance.$100 later, I was on my way with wheels being in worse shape than before from the balancing stand point. Would love to hear your story and what had to be done to address. My latest theory is that it may be the brake rotors, but of course the dealer is saying all is good there.
Hope the wife is enjoying her A4!

Thank you!
Vlad