So what you should try is to run a pack, and never discharge after its run in your car.. Let it cool or save it for next week, and just charge it without discharging. Do this a few weeks, then compare on the bench to a pack that you cycle normally (discharge and tray) on a regular basis. Thats really the only way to tell.
Right ! A year ago, when I got my first NiMh packs, that is just what I was doing. Race, charge, race, charge. Ocasionally I would dump the packs before charging for around 2 min. with the bulbs, but that's it. Having learned more since, I feel a big difference in power after a full dump and tray before charging.
Even on those old packs from a year ago that are now for practice.