Stu, watching the video your car is definitely over-geared and/or over-timed. Notice how everyone catches you through the sweeper as your car bogs down - that's where the heat gets generated. Out of the corners they have you for breakfast. When the orange and white car crashes and then catches you, your corner speeds are similar but he out-accelerates you from every turn.
As for the driving, you are trying too hard IMHO. You seem to throw the car into a corner, miss the apex and have too much speed so making you exit wide. Watch the front runners and see how much closer they are to the apex and tight on the exit.
Because foam tyres never completely lose grip, it is assumed that cars can always go faster. The tyres
are losing grip and that means you can't vary the line effectively. When the front end loses grip, the car will not go where you point it, it will go where it has enough grip to go, and that usually means missing the apex and exiting too wide.
There is a sweet spot for fast cornering on foam tyres and it is rarely flat out. Just below it the car will in effect turn itself. Try backing off earlier and rolling the car through the corner and you'll see how quickly it turns and how easy it is to hold your chosen line. Speed that up until you are back to missing apexes and exiting wide - somewhere in between is that sweet spot.
Just my thoughts, hopefully you will get others.
