Dear
BobTL and
irishguy28:
Please check my latest post where I provided an update on the latest miles amount to upgrade from Premium Economy to Business class on the PAR-JFK route:
https://www.flyertalk.com/forum/31781010-post34.html
Yes, they are fixed amount cost and follow an upgrade award chart. I just upgraded one leg from "W" to "O" (plenty of availabilities) for only 10,000 miles. An amazing deal!!!
Cheers,
-vinnyc