Wow, this is a totally NOT boring conversation with Giomen, Neil, Cnfhbr and syzygy !!!!!

If I am not mistaken, the D25xxxxx.JCV file was introduced with only 37xx as (Photoreal) LaneAssistFull (the ..."big" file or "High Resolution") with [Only registered and activated users can see links. ]
All other nuvis (755T, 765T, 775T, 785T, 855, 865T, 885T, 1340, 1340T, 1350T, 1370T, 1390T, 1490T) were still using the D12xxxxx.JCV file.

With [Only registered and activated users can see links. ] Garmin replaced the D12xxxxx.JCV file with a (Photoreal) LaneAssist file D30xxxxx.JCV (the ..."small" file or "Low Resolution" file).
Because this JCV file had half the size of the 37xx JCV file and because all the other nuvis had half the screen resolution (480x272) of the 37xx (800x480), I believed (and I think most of you did too) that the images in the D25xxxxx.JCV file of 37xx were of "High Resoloution 800x480"!!!!!!
How could I ever imagine that Garmin was giving to all the other nuvis (except 37xx) fewer images in their JCV file, or that the images for the 37xx were of "Low Resolution" 480x272 ??????????
Garmin got me fooled for so long....

So, from what I've read above from Giomen, Cnfhbr and syzygy, and to round things up:
- The so called "High Resolution" D25xxxxx.JCV (which in reality contains "Low Resolution 480x270" images) is for 37xx, 13xx and 14xx (according to Giomen after firmware update) and also works OK with 765
- The D30xxxxx.JCV........ what is the use of it, only for nuvis with limited internal memory???