I figure since I was so vocal in complaining about my car's vibration, I should mention that it's finally gone! After balancing and new Turanzas didn't make any difference, they found that one wheel/tire combo couldn't be balanced (Hunter Roadforce) and when they replaced it with a new wheel off a new car on the lot: voile! The ride is much improved and there is minimal vibration. Four months of frustration, but now I think I've finally got the car I wanted. I'm sure flatspotting will be worse when it gets cold again, but I hope this is the end of this.