Just got Cab three days ago. On highway get sound that sounds like turbo whine...is it the tires?

Hello jparo-- I can't give you a 100 percent answer via cyberspace (because I can't hear that specific sound), but a real good mechanic who worked for me one time always kept reminding me that the tires are the only place that your car touches the road. Therefore a lot of those type sounds are indeed caused by the tires. The Michelins on my car make a similar sound. Get used to it and enjoy that new car. Drive carefully. Good luck from Bovan

jparo - I also have an S4 Cab and was somewhat surprised by a whining / whistling sound that my car makes. However, in mind, it is at certain RPMs (typically around 2500 / 4000), and only for the first 5 - 10 minutes of operation. I was informed by my Audi mechanic that this is not to be alarmed over as it is a function of the chain-driven technology and the mechanism for lubricating the chain. Apparently, all Audis that have the 4.2L V8 have this issue, but is not a mechanical problem. Does this reflect your issue?