I know that a higher class SD card speeds up the transmission of information. Presently, I'm using a class 4 SD card which is fine for the most part. But some navigation commands happen when you are very close to the turn. I wonder if using a faster class 10 card would increase that speed? Is there anyone out there who has moved to a higher class SD card and noticed an improvement in speed? Thanks.

I don't think a faster SD card would help in that situation. At that point, whatever the software has to load from the SD card would have been loaded to the device's memory anyway. The only way to make the navigation commands more timely is to drive slower as you approach the turn.

Of course the faster SD card would make your navigation software start-up/loading a little faster. You would notice the difference of a faster SD card when copying files from your pc to your sd card or from sd card to pc (when updating maps).

I think that you're correct but I thought I'd ask anyway to see if ANYONE tried it and found it to be successful. I kinda think that the higher class cards pretty much only read\write the information faster but ultimately it's up to the program itself. The signal goes up to the satellites and returns; it can only go so fast.

I tried almost everything from old 128mb SD to class10 SDHC on my systems.
Only major difference are the loading times, for the rest there is no noticable difference.
As for delays and instructions: never noticed any difference either, unless using TTS / 3D features and so on an underpowered device.

I've personally only noticed a very slight increase in performance of the tts with the units i have out there with class 10 cards as opposed to the class 4 (that usually gets shipped with the no-onboard flash units). I tell my co-workers how to find their preferred hardware and then I set them up with a copy of my unit so there's quite a few different styles I have to deal with. On the systems that have no onboard storage there was only one where the class of card made much of a difference (according to the owner). It might have to do with the actual transfer speed of the card reader built into the device possibly. I do notice with the onboard flash systems some transfer the files much quicker than the others when installing files or updating their maps.

To go slightly askew but relevant... another interesting note in reference to loading speed. The guys with the lower res units (mostly 4.3" - 480x272) screens load the maps and overviews much faster than the guys with the 800x480 5" and 7" units but calculate at roughly the same speed.

Best loading speeds all around are on the primo-android backup I have on an old acer phone and the tts is usually spot on unless there is a heavy background load.