After purchasing my long awaited GX470, I discovered there is a noticeable vibration at 40-50 miles per hour or 1500-1800 rpms. The dealership (Lexus of Orlando) has informed me that after conferring with Lexus USA, this is a known problem that they have no fix for at this time. I find this unacceptable for Lexus, this is my fourth Lexus purchase and have never experienced like this. Does anyone else have any further information on this topic or suggestions?