The HQ tracks should be a little more bright than the standard tracks and Brands Hatch is an add on and not sure what lighting it is using.
Go to the .gdb files for the track and compared it with a track where you like the ligting.
An easy fix is to change the time to 6-8 am or 17-21 pm.
The best time depend on track latitude and track race date.
Flicking textures are hard to completely eliminate.
Are you using the steam gtr2.exe or the No-cd gtr2.exe?
The steam .exe uses a different way to calculate the clipplanes.
So check you defview.com file in the userData folder
For cockpit view use something like
ClipPlanes=(0.52500, 500.000000)
the No-CD .exe are something like
ClipPlanes=(0.17500, 500.000000)
increase the '500' to 4500 to eliminate the headlight flickering but that will/might course some slight texture flickering!
The first figure 0.52500/ 0.17500 you want to mage as large as you can to reduce texture flickering but small enough so parts of the cockpit isn't 'cut away.
Also and more important use Nvidia inspector profiler.
Do not use the AA in the config.ini use the Nvidia profiler!
Under gtr2 and the other gmotor games.
Antialiasing compatibility select Diablo III or Stalker Believe the important is figure ending in c1
And also Anisotropic filtering mode select User-defined/off
Anisotropic filtering setting select 8x or 16x
What kind of AA you can handle is up to you.
GTR2 FFB feels better if the fps are +100.
There are a few more tips to get gtr2 to run at it best but this should get you started.
