Bikes and cars? Black gloss finish but now needing something to remove minor scuffs and scratches? Nothing too abrasive?
Autoglym super resin polish is OK . Not very abrasive but does contain fillers which will mask the scratches/swirls in the paint work. There'salways Tcut, but you have to be very careful wwith it as it's very abrasive which makes it easy to sstrike through the paint.
There might be better now but I like farecla- the rubbing compound breaks down as you work so it's automatically like moving to a finer compound.
If you can feel the scratch with your fingernail then its to deep to remove. Autoglym is unlikely to remove anything other than the faintest of swirl marks but it will temporarily fill in a lot thus masking them.
T-cut?
Forget t-cut you need a dual action polisher and a compound such as poor boys SSR-2, depends if you have light scratches or swirls etc.
Go on the detailing world forum for stacks of info
Local paint sprayer if too deep.
Sudocrem.
gtechniq p1 - is the best stuff I've ever used.
We have a black car and have great results with Tcut colour fast