well i belive i can trail brake to some extent in GTL. and in my
training video you can see it in action.
I find GTL really does like trailbraking and you can make up a lot of time by using it, however its not that easy to do. Plus it only really works with longer corners, while possible on short corners and tight slow ones its much more difficuilt and i find you normally end up stuffing up or comprismising your exit which more than outweights the slight advantage by trail braking in the 1st place.
Say for dijon turn 1 you can brake just before the bridge, about 2 car lengths, you do all your braking before the corner then as you turn in your off the brakes. If you trail brake you can probably knock that down to at the bridge or even a car lenght past, 2 - 3 car lengths later. So you brake 100% just past the bridge then you get to the corner and turn in, now your down to 80% brake, then you gently decrease the brake pedal more and more the further you get into the turn, If you just kept the brake pedal constant or didnt ease off you would exceed the tyre grip level and lock both fronts and just go straight, this is the tricky part as its not easy to feather the brake pedal which has no feel and turn in at the right time and balance the car with the gas pedal and keep an eye on your surroundings etc etc. It takes some practise. Normally i can feel when the wheels lock via the steering wheel, or hear it via the skid noises, so useing these cues i can tell whether to increase or decrease the brake pedal.
Anyway the advantage is you brake later and normally have much faster entry speed, however you have to be careful you dont jepordize your exits as well. I normally trail brake right into the apex then power out.
For trail braking to be decently possible you have to be running as much rear brake as you can control, some drivers use so much rear brake bias that they use some gas to stop the rears locking, personally i dont really use this and i only use the gas a few times when braking to settle or balance the car, I definetly dont have the gas pedal pressed down the entire time i brake.
Anyway i hope you can make sense of my post as im not sure if its readable..