When loading an .spr replay with AIs in it and clicking test drive, the AIs just stand at the start and won't move. Nothing big, but worth to look at it.
I'm not sure if this is expected or not. When you watch a replay that contains AI, then go to 'test drive' mode and start the race, the AI will just sit at the start grid.
Duplication
1. Create a single player race with an AI player, as well as yourself
2. No qualifying, 5 laps, just set off, drive for a minute, then save the replay
3. View the replay, press esc, and choose 'test drive'
4. Start this race. You'll notice the AI never starts.
You can probably also just go from the attached replay and start a 'test drive' from there.
I don't know if it is a bug but I found something :
Start a race with AI,
Make some laps, press ESC and click on "replay" or press 1,
Quit the replay and go to the replay menu
Watch a few seconds of your replay press ESC and click on "Test Drive"
You can drive the car but the AI will not move an inch