update on an old thread
At this time no changes have been made. Allow me to explain what is occurring. The perceived discrepancy comes from the filesystem block size. The iOS filesystem uses a block size of 4KB. That means every file is stored in multiples of 4KB. So a 10 byte file, a 500 byte file, and a 3.9KB file all use 4KB of storage. A 13KB file uses 16KB of storage, and so on.
These two factors combine for the perceived discrepancy. Another example is if map download set of only 20 tiles is 100KB. But each tile is 5KB of data and takes 8KB to store, making the actual disk usage 8KB*20 = 160KB. As you can see this can really add up when you have many sparse road or terrain tiles that are really only a few hundred bytes, but all require 4KB to store.
All the best,
so there is no "fix" possible from the way it sounds