Please tell us some of your exact routes so that further study may be made.
Salt Late UT to Denver CO is one lateral route. Seattle WA to Missoula MT is another. The distances should be stretched or compressed in one of those two routes if we use the flat earth model.
In both cases the odometer was more than able to stay in sync with the mile markers on the highway.
I only thought of it as I was traveling recently, but regardless of
my route, if the odometers and mile markers didn't match up around the country, people everywhere would be constantly trying to get their odometers fixed. This would clearly expose a conspiracy to falsify maps.
As for the "not having a FE map to invalidate" all the disk theories (especially when taking circumnavigation into account) include either the southern hemisphere being stretched laterally or the northern hemisphere being compressed laterally. It is pretty well established that there is a FE claim that GPS is rigged and the RE distance data is fraudulent. My point is this cannot be so, as odometers would have to change their measurements depending on the amount of lateral travel vs the latitude of the travel, and a car cannot infer this without GPS. Without this sort of complex rigging, an odometer could never stay in sync with highway mile markers, across different latitudes.