Well I am currently doing the SuperGT(as in right now) with my Mazda 787B Stealth(Saved nasty rainy Suzuka for last...)
It will easily win. If you have the Minolta Racer(I believe you win it from Like the Wind A-Spec that would be a comparable car)
For the German Touring I used the Lexus IS Racing Concept same as I used in A-Spec. It will do just fine tho I can't even get my highest level drivers to keep their cool/composure long enough to not cook their tires and mess it up near the end on the Nurburg race so best I have managed on that is Silver tho I will mess with the cars setup a bit and see if I can get it a bit less tail happy for them.