I've had problems with my Series II GS300 since I bought it second-hand a year or so ago (I posted a few times back then) - it was handling like a dog and chewing up the front tyres like there was no tomorrow. Lexus said there was nothing wrong with it and wouldn't do the tracking as part of the warranty cover, so I just put up with it for a year.
Recently I took it to Tony Bones (wheels-inmotion.co.uk) over at Watford, as suggested here. He found that the geometry was well out of spec. and sorted it out for me.. it's made a huge difference to the car, no more drifting, no more hanging on for grim death when going over bumpy roads, and it goes where I tell it to rather than meandering off wherever it feels like. Bliss.
Seriously - I can't believe what a massive difference it has made.
One things he said was that he often saw GS300s and IS200s that weren't properly set up out of the factory - he also reckoned that mine had a manufacturing fault that meant he couldn't adjust it to the factory spec.
He reckons that keeping the tyres slightly overinflated should sort it to some extent but I suspect it explains the really fast tyre wear (only on the front) that I've been having.
I'm going to write to Lexus and ask if they can sort this for me as I thought there was something wrong with the car since a few days after buying it. What do people reckon my chances are of getting Lexus to pay something towards the extra tyres it's going to get through?
Anyway, if anybody has got a GS300 that seems to have a mind of its own, take it to see Tony and he'll put it right.