It's only ever booked into a higher fare class when taking the limited time offer at initial booking. It gives you a "5 minutes to accept this offer" message. If you take it, it books into a new fare class. If you decline and come back later, you're simply buying an upgrade.
And FWIW, I have not seen this at-booking offer in several months.
Originally Posted by
raehl311
Are you sure?
I just bought a ticket, EAU-ORD-LAS, and was offered prior to purchase the option to upgrade ORD-LAS to F for $199. I didn't do it then, but shortly after making the purchase, I figured it's a 4-hour segment and a business expense so what the hell, and went back to the reservation, and the same $199 option was still there in the premium travel options (along with the mileage accelerator buy-up option.)
Purchased that, and while the far code still starts with W, it shows First Class (A) in the reservation.
So, I didn't buy it at purchase or at check-in but in between.
Suppose I can just come back and let everyone know the result in a week or so.