I've used Novus with some success on a 1995 Lexus sc400 - It's a 3 step process 3. heavy grit/scratch remover 2. medium scratch remover then the 1. plastic cleaner.
All are liquid.
novuspolish
Did NOT make the
headlights perfect but then again I only did one application with sample sizes - I would bet if I bought a full size and 2 or 3 applications, I would have had it near perfect.
Otherwise, your options are for 3m kit that physically sands the scratches off...
To me, If I can get it 90% with only liquids than I am happy.