I have read the comments on this topic with interest. It is now two years since I reluctantly parted company with my GS 300 SE-L, and still miss it to this day. The reason I changed marque.....ridiculous road tax cost, and loss of faith in Lexus dealers.
Interestingly I had both rear calipers replaced under warranty, and Peter Whitaker appears to believe that Lexus technicians are something exceptional to be able to work on such a complex vehicle....really thet just plug the OBD meter in, read the codes and you pick up the tab.
I am in the Hayne camp, I lost faith after my GS had the Xmas tree lights, ABS, Traction control, Engine management, you know the symptoms, they are all over this site. Took it to Lexus Dealer, OBD meter, yes Sir, 2 x oxygen sensors and ECR, that wil be £2500 please. When I bumped my gums, Lexus did parts half price, and dealer half price labour, now £1200.
Thank god for this site, following forum discussion, bought new fuel cap, £26, and problem solved, no more issues. When the engine switched on, fuel tank pressurises, and old filler cap rubber, (five and half years old) lets in air and sets of all the light. Now i aint no Lexus technician, but if I can find out that information, surely Lexus technicians can, but of course not as proffitable. Incidentley, Lexus were replacing the oxygen sensors and ECU until the car was 5 years old as they knew they had a problem but never admitted.
Still miss my GS, smooth, powerful, a cut above, but had my new motor two years now, and the dashboard doesn't creak or rattle. I would never rule out a Lexus return though, fantastic cars, and coffee, but dealer confidence an issue.