Need some help and advice.
I own a 2006 Lexus IS350 that I bought new last year in October and have put over 24K miles in 8 months. At about 16K I noticed a slight oscillating vibration (1-1.5 seconds of high frequency followed by 0.5 seconds of no vibration). Mentioned this to the Lexus service and they noted unusual wear and cupping on the tires. Short story, have had the car aligned, replaced and balanced all 4 tires (replaced them with the new Eagle F1's) without solving the problem.
Over the last month it's gotten worse. The vibration/shuddering is first noticeable around 70 mph, but only faintly on very smooth roads. It get's more noticeable at higher speeds. At 80 mph it's annoying and that's about where most of us in the Midwest set our cruise controls on I-29 where I spend about an hour each day.
Have taken it in to the Lexus dealer (Superior Lexus of Kansas City) 3 times. Two times a senior mechanic road in the car and verified what I was feeling. He even suggested it might be a drive shaft that was out of balance. However, and this is where it gets really annoying, the service manager called and said she would refuse to fix the problem since in order to duplicate and diagnose it her mechanics would have to drive faster than the posted speed limit.
So I'm stuck in a catch 22. They'd like to fix it but can't since they won't allow their mechanics to diagnose it.
I think it's a safety issue and am left with a number of alternatives. Take it to an independent mechanic and pay for the diagnosis and services myself; dump the car (which otherwise I love) and buy a car that is designed for highway speeds; travel to other Lexus dealers to see if they will diagnose and fix it; drive it until something major happens (it is getting worse). Or, and this is option I'm least in favor of, seek legal remedy.
Anybody out there in Lexus land have a similar problem or have solutions that'll be palatable?