So far every race in Career for me (44% in) aside from Go Karts has been a rolling start, 10 seconds behind the lead car in last place, which is such a big disapointment for me

. You then have to drive 3-5 seconds a lap faster than the lead car in order to catch up. Each race is like giving a Caterham F1 car to a driver with a 10 second lead, and then saying to Sebastian Vettel in his Red Bull "ok seb, pass him in 2 laps", and he will do it with ease.
It's just not realistic, and the bad part is that the AI are often driving cars that are faster than what you're driving. But it gets worse, because on the final lap the AI car will slow down to allow you to catch up. For this reason I'm beating Corvettes Z06's, NSX Type R's, BMW M3's etc in my 190bhp Renault Clio. Then sometimes the AI is different again, the National A championship I raced in my 1991 Acura NSX, racing against comparable cars (some faster) and I pulled a 20 second lead at Bathurst in a 3 lap race.
Additionally I notice sometimes when you pass the AI they swerve about nervously and then drive really slow, so you look in the mirror 2 seconds later think "wtf how is he so far back". This also happens especially if you lightly bump them as you're passing, they slow down a lot. Lastly, later on there definitely is some challenge in some of the later races, but not because the AI are so fast but because you have 3 laps to work your way past 9 cars, sometimes on tight circuits where it's difficult to pass, with mobile roadblocks at every turn, and with a straight line speed disadvantage, but yet you still win.
It's just not racing for me at the moment, every race is a race through traffic to try to catch the lead car, once I do catch up.. despite the fact they can sometimes pull the lead to 15 seconds in 2 laps, I still managed to catch him in the final lap and pass him so easily he might aswell be parked on the side of the road.