Over NYE, Test Track broke twice on 2 days we were at Epcot. We went to the Fastpass line to ask if we could get one to use the next day since we had a PS in MGM and had to go and the ride was still not open. When we asked, the CM said that Test Track always honors fastpasses regardless of the day, time, or even the year issued since it shuts down a lot. He said to hold onto the ones we and and we could use them whenever we want to, even if we don't come back for 3 years. We did keep them and plan to use them in February so if it doesn't work we'll let you know.
At RnRC we also got a fastpass because when we went to ride it, about 10 minutes before park closing on 12/29, it was closed for technical difficulties. The CM was telling people to come back the next day. My family went on ToT and I went to ask the CM at RnRC if he thought they'd fill to capacity on NYE and he asked if that's when I'd be back at MGM. I said yes so he said "oh, well I can't tell you to ride RnRC on NYE without a fastpass" so he asked how many people were in my party and handed me 3 fastpasses for the ride. They said 3:40-4:40 12/29/02 but he said to just use them and explain that hte ride broke down when we were going to ride. So I think you can use them whenever for rides like that.