If you can't get it to work on wheels, you may be out of luck...get them plated, use Alclad or Spaz Stix (supposedly SS has a new chrome formula that's stronger and more reflective).
As for window trim, try cutting a large piece that will cover the entire area without bending around corners or splicing pieces, and then carefully burnish & trim.
If it can't be done in one piece, plan ahead so that splices are at sharp corners or transitions. Aside from having a model car body plated and then masking it off prior to painting, your choices are relatively limited, and you'll just have to try all the various possibilities and see what works best for you. I would never have the patience to do Alclad window trim; it's just too fragile for the handling needed to be done between doing the trim and finishing the model...and forget using a polish afterwards to do a final detailing.