First, I'm not claiming that this is a generic fix for the vibration and wandering that some owners are experiencing. Just passing the info along. I have an A5 with 245/40R18 Pirelli P6 Four Season tires. The car had a tendency to wander slightly at hiway speeds above 50 mph and in the 62-67 mph range I had a slight, but noticeable, vibration in the steering wheel. My vibration was not severe like some have reported. Between the 62-67 mph vibration and the 50+ mph wandering, the wandering was the most annoying. The car also had more understeer on curvy roads than I expected. More than my 2002 A4. While checking the tire pressure in my motorcycles I decided to check the A5. The tire pressures were 32 psi for all four tires. The sticker in the door indicated that the pressure should be 36 psi front and 35 psi rear so I bumped it up accordingly. I've got approximately 150 miles since doing so and the wandering tendency is completely eliminated and the vibration is gone as well. The steering response, while still having an understeer, is what I would expect from a nose heavy car and is less than the A4. That 3-4 psi difference seems to have had a significant positive impact on the road feel of the car. The effect is actually quite similar to my experience with an underinflated motorcycle at normal highway speeds. Running tires down 3 psi on my bikes has a significant impact on cornering feel. Running lower pressure is good at track speeds of 120 to 160 mph but not so great at 70 mph. So, you might wanna check your tire pressure. The lower the aspect ratio of the tire, the more impact running a low pressure will have on feel.