I have to tell you the answer is elbow grease. Cant get around it. If you
have an older vanagn you are in luck. That old paint is protected under
that white oxidation. You cannot beat it with new paint.

 With new paint , you are always concerned about a ding or blemish.It can
drive you nuts, and you will never think of you van the same anymore.You
have to protect that perfect. With old paint, (20 years old)you know it is
not perfect and another small ding can be seen as character.Much less
stressful. And new paint just  dosent have the depth or thickness.

 I used Dupont posishing compound. This is so common a product, your
grocery store may have it.Do not use Dupont rubbing compound! To protect
this new shine ,I used Maguires wax. Protects the shine very well. Without
wax , the shine will oxidize back to whence it came in about 1 month. Elbow
grease over a few weeks will do it.