I think there is not such a thing like " best car " in that race ,a race that used to race just for griding and that's all.
Many cars can compete there with 100% success , fast cars ,slower cars ,easy cars or difficult cars .
No matter how fast you are it depends on the AI ( and weather) if you will run close to 30 min. or close to 32 etc.
Its mostly what are you looking for, you want challenge? You want " safety" ? You run in difficult mode or an easy one ? and many other things anyone want .
I try this race with different cars but the most " worry free" is what i use from the beginning.
I took the nissan motul ( 16 ) ,put intermediate tyres all the way and FM 6 from the beginning.
Its easy to get 6 or 7 laps without pit and without worries about rain and when .
The setup is slow on straights but you get your blood back during the final section cause can go flat out.
Lapping at 4.31 ,more or less and its easy to finish under 32 min.
Of course is on easy mode , try it once on hard and couldn't win ,end up third .
Settings are like this
View attachment 1236135
And when weather helps i challenge my self for faster lap and faster race if silly 0.500 penalties not applied.
That's my option for that race and for me is quite enjoyable mostly cause the grip its outstanding with or without rain ( not heavy rain ) and you just drive .