I recently got a Mini Cooper to do 150 variable throttle laps with no deslotting.
First I cleared all it's data in the Pace Car Editor.
Second, I placed the car at the very beginning of home straight to give it a good run up to the start/finish line.
I laid down One clean lap of around 9.5 sec with dynamic and progressive braking turned OFF and refreshed the data in Pace Car Editor
I let it run a few fixed throttle pace laps at a start speed at 35-40% to see how fast the car can be going without coming unstuck on the last corner (a.k.a. "Tourettes")
With pace car running turned OFF, I placed the car at the start of the straight in the same lane i recorded the lap with, selected variable throttle, target lap time 13.0 secs, start speed 40.
Turned pace cars on.
Noticed the car was slowing down before it got to the corners and the distance before each corner was getting greater and greater. This told me that the car was too slow starting the lap.
Reset position, start speed to 50.
Car made it around to the straight before the final turn perfectly but slowed right down on the straight, then took off and deslotted around tourettes (#%#%@). It did this quite a few times. Started to think that this sudden surge at the wrong time was not to do with the throttle recordings but because it was trying to achieve a lap time and thought it needed to slow down for a while before picking up the pace again and since it hadn't yet completed a lap it wasn't 100% sure of "where it was on the track" and didnt know how far from the start finish/line it was.
Each time the car came off, I waited a minimum of 10 seconds before putting it back on and letting it keep going because i think i read that if the car goes more than 50% oer the target lap time, SSDC assumes it cocked up. After percevering with my assumptions about what the car and software was thinking, it finally got around the last corner (JUST!) and drove down the straight to complete a full lap.
After that, it was in business. Completing a lap seemed to help give SSDC an idea of where the car was on the track so to speak. I'm guessing it took the lap time of the lap and scaled it to it's throttle recordings. The car followed the throttle recordings perfectly and started to improve it's lap times from 15sec all the way down to 10.9 and ran happily for 150 laps
I stopped the pace car running, keyed in another mini so i could drive against it, and had to reslot the pace car on the final corner all over again but eventuallly, again, it settled down and was keepping a good pace. I had to push hard in a few sections of the track to keep ahead of it
Hope This Helps