When you charged them did they get hot? NiMh peaks at 120-130F and if they didn't make it to that kind of temp, they didn't get much of a charge due to something called a false peak. I asume your friend is using a peak type charger, that's the best for NiMh.

Voltage on a NiMh pack means little since the cells recover voltage pretty quickly, its when you put a load on them like you did in teh car that lest you know whats there.

NiMh packs can wind up sitting on a store shelf for a long time and the batts self discharge so there's nothing there. They can be brought back by cycling - repeated discharge/charge cycles if they're not so old that they're compromised.