I averaged 18,000 miles each on the first 4 sets of Bridgestones on the F6B. I am not sure how I am riding differently than you but I do mostly straight line riding at 80-85 mph in the Florida heat. That being said I installed Elite 4's as my 5th set and we will see how they hold up. So far they seem a little "slippery when wet" compared to the stones.
As far as car tire handling....watch this Goldwing at the Dragon. It does not seem to slow him down!
https://www.youtube.com/watch?v=37XLJNLpzxQ