As for Grid placement, if by randomized you mean in some races you're in a different position than others, I don't necessarily call that randomized placement. I've played Grid sp through several times and invariably within the same difficulty level you always get positioned in the same spot for a given race, even though the position varies from race type to race type.
I've also noticed that you do indeed consistently go back in the grid as difficulty level goes up, it wouldn't make sense any other way. Conversely however, for some odd reason they'll place you at or near the back on certain races that are very hard to win, yet put you in the pole position in ones that are extremely easy to win, such as the non Le Mans races you do in the Audi R10. That car combined with pole position = easy win on any track.
lol sorry but I disagree. I just started about 15 (if not more) times the same race (F3 race where you're against Ravenwest) to get a better placement for my team mate Tom Rockford, in simple difficulty with catch-up disabled
It's absolutely not like you say, placement is actually random with probably modifiers to the randomness (like ravenwest getting more chance to be in the first 5 places). I was placed two times 7th the other times between 9th & 12th. So no you don't get positioned into the same spot for a given race in a given difficulty.
to test restarting a race just pause the game right after the race started & return to the garage then go back & load the game back, it will re-randomize placement.