What's the best stuff for using on instrument cluster plastic, mine has a lot of fine scratches I'd like to clear up. Don't say Plexus because I've tried to get it in the UK and I can't - typical useless Britain!
Mothers Plastic Polish will remove hairline scratches...I've used it and it works well.
Just be careful with instrument clusters; they show up ultra-fine scratches more than anything. Gauges are different...no where near as sensitive to scratches.
Mothers Plastic Polish is less aggressive than Megs PlastX - similar to how Mothers Scratch Remover is less aggressive to Megs ScratchX. Its meant to be ultra safe for the average consumer, so multiple applications may be required. It seems to me that Mothers make products to be idiot-proof, while Megs make products to be impatient-proof. Just different approaches, I guess.
Also be careful with your choice of applicator...start with a very soft applicator like foam and see how it goes (work the polish in well...it takes longer with foam). Even a good MF can cause some issues with instrument clusters...pesky things!
I've also had good success with Novus plastic polish, which comes in three levels of abrasive strength - just like paint polish. You'll find info here: http://tops4less.com/novus-plastic-polish.html
Renovo seems to be the best product I've used to remove scratches from my plastic window on my BoxsterS. I've tried everything. With an orbital polisher for best results.
I got some Plexus, it's done a very good job on the instrument cluster and all my other gauges (Defi BF), I don't think I'll use anything else as the plastic seems quite soft on the cluster and the Plexus has done a good job, you can't really see any micro scratches now.