Wow.
My first play of GT5 online for 3 months, and quite incredibly, it's even more broken than it was before. My very first race, I find myself 30 seconds out in the lead, with the rest of the field two laps down.
Second race (and subsequent races), massive carnage at the very start, because half the grid do not know about the wonderful START START bug on Daytona.
Third race, unbelievable lag. The worst lag I have probably ever seen in an online game. Ever.
....
It is safe to conclude that Polyphony Digital have no idea how to code online, and should probably start hiring people who do actually understand. In the absence of my GT5 disc, I was playing a number of other games online, and none of them had the amount of problems GT5 had. I don't know what the issue is here, but I find it baffling that a studio that is meant to be at the forefront of technology can construct such a broken online system.