Do I blame Google or Honda for that?

You sure it isn't the problem of the network. Handover from one cell phone mast to the next is not a problem per se for voice, but lost packets of data on SatNav apps must be pretty devastating for maps, especially because the Goggle app downloads maps as and when needed in small chunks. Though if you surf for "how to" you can download the maps permanently, but prepare for areas before going!
I use maps.me for walking, on a phone with no SIM card.