My SC430 was beginning to get unpleasant to drive on motorways - it was decidedly vague in the straight ahead position and felt as though it was wandering from side to side. On checking the tyres, they were visibly worn on the inside edges - so it was pretty obvious to me that the tracking was toeing out. The first check I had done said that the tracking was OK, but I didn't really believe it.
So I had it checked on a laser four wheel alignment bit of kit and it showed that one front wheel was toeing out by 1.5mm.
It was then adjusted to give the correct toe-in (0-0.6mm per side) and hey presto! it now drives like a dream. It just sits there on the road without needing continual adjustment. It feels much sharper on the steering.
Just thought this might be interesting.