when you're ingame, enter 'edit tod' which means Time Of Day, a relative new feature. From there, you can tweak each TOD point & get the brightness value as you intend.
There's also sunny = 0 - 10 or clouds = 0 - 3, just choose a value from the range I've indicated.
Last thing, the range of sky values was re-normalized to 0-1 range along with other variables, so keep an eye on it & compare older special.inis to newer ones, to get the big picture !
Make sure you read racer.nl, it's full of info...