Rival mode question

Does the ghost car only loads when starting the race?, I mean, if I beat that driver and go for another then the ghost is not loaded, do I have to leave and start the race everytime if I want a ghost car?.

Also, how does it work if I take racing line out, is my time still compared with ppl who use racing line or other assists?, if someone goes full assists is still agianst ppl with no assists?

Unfortunately, yes.