So it would seem the Fiesta driver didn't know about the accident blackspot, in which case should he have been travelling between 80 and 100 MPH , 3 up in a Fiesta if he didn't know the road.
Either that or the fiesta driver knew the road well and didn't care about the dangers. If i'm honest I still cringe about the stupid things I used to do in my youth in my first cars but i've been LUCKY as have most of us, if we're honest. To me this seems like a tragic accident with an UNLUCKY scapegoat.
Based on what evidence i've read so far (which of course may not be all the evidence) I don't think he should have pleaded guilty, but I am fully aware how solicitors can try and persuade you to trust them to do what's best, especially when you're vulnerable and unable to fully think straight.