I was in Nova Scotia, the local road on the paper map was straight to my destination. Standing on the ground, it looked like it had nice quality pavement with wide shoulders. My Garmin told me to take a different route with a combination of national and provincial highways that was twice the distance as the local road. I could not figure out why it did not pick the local road, checked automotive routing, cycle touring routing, and road cycle routing, all were the same. I rode my bike on the local road, it was the right choice. This was using my Garmin 64.
Different device and location:
Last summer my Garmin Nuvi was telling me to drive hundreds of miles out of my way, the gravel road that I was driving on was direct to my destination. I think I had about 25 or 30 more miles to drive down this gravel road. The county paper map told me that the gravel road was the right way to go. The Nuvi had the Garmin automotive road basemap from the Garmin Express program.
I had my Garmin 62S in my vehicle, since I had about a half hour of nothing to do but drive to my destination, I pulled out the 62S and checked it too. It also told me using Automobile Routing to drive hundreds of miles out of my way. But the 62S in Tour Cycle routing took me to my destination by following the gravel road I was on. I do not recall which base map I had enabled in the 62S, but I am quite sure it was one of the Open Street maps. But not sure if it was a topo map or automotive map, since I have both options in the 62S.
So, if you think there is a good reason that both Garmin devices in automotive routing was telling me to drive hundreds of miles out of my way, mostly on paved roads instead of roughly 30 miles on gravel, I would like to know why.
I am a retired geological engineer, I worked with maps every day of my professional career. I bought my first Garmin 24 years ago and have owned a half dozen generations of handheld Garmins since then.