I treated my shared Jodel every 2 or 3 years with Autoglym Super Resin polish. It been heavily tested with every paintwork imaginable but if you favour another polish system there is an alternative. The Autoglym pure clear topcoat is incredibly simple to use and gives that long term ice sheet finish and liquid beading. Price is mid range auto polish and not the hype ridden alternatives like those plaguing Facebook at the moment.
Brilliant performance on fabric, composite and metal.
Rob