I achieved one more step along the path to Dirchie AI nirvana this afternoon by implementing a time trial mode with a recorded ghost of your last best lap.

I was having all sorts of trouble getting the ghost to sync with the lap time, he was always a bit faster than you even if you beat his lap time. The solution was to put the game back into fixed time step mode (so your update method always runs at 60fps).

Good ole Shawny Hargreaves has a great article explaining how XNA handles it.

What does the ghost have to do with the AI? I’m planning on using the best ghost data as the optimum racing line for the AI drivers. How exactly I do this… I don’t know…. yet.