I had the exact same type of stain, an amber colored stain that got on my car and completely dried and incorporated into the pain the first week I got my IS250AWD. it was tungsten Pearl so it was easy to see. I had a detailer try to take it off... he used thinner and actually scraped a chip of clear coat off, but before that the stain wouldn't come off. At that point I took it to the dealer, they tried to wet sand it, got lighter but didn't come off, eventually the dealer just repainted the L/R door for me...