Can't figure this out. But it happened twice (2 different SD cards) so I don't doubt.

Take all my unused big apps, and apps that don't care where they reside and move them off SD card and back into main memory. Card is clean and empty. Format card. Install TomTom and maps (to card). Have 3.9 MB free in main memory.

Now I take PowerRun and move all those aforementioned apps to the card which gets me up to about 17 MB free. Then I move them back to main memory. I now have 8.9 MB free. Where did the 5 MB come from ?

Before this, I had done the same procedure minus TomTom to my 128 MB SD card, same thing happened, picked up 5 MB.