Any maps you have in your car or in an Atlas somewhere are inaccurate. This is because cartographers and map makers have, over the years, made accurate distance measurements and found that they cannot be displayed accurately on a flat sheet of paper. This is, all by itself, very strong evidence that the earth not flat because, if it were flat, their measurements could be accurately displayed on a flat map.
As evidence of this, I show below a map of the United States along with calipers that are used for the scale of the map. The calipers show the distance in pixels between the various cities of San Diego, California; Miami, Florida; Portland, Oregon; and Portland, Maine.
For scaling purposes, we use the Miami, Florida to Portland, Oregon distance to establish this map scale of 4352 km = 755 pixels, where 5352 km is the established distance in km from Miami to Portland.
The established distances are taken from maptools.com and the map itself was taken from worldatlas.com
The image below shows the distances between the various cities in pixels, then the distances in km using the scale above, and then for comparison, actual established distances between the cities:
You can see that the map error is as great as 14.4%, which is because the earth is not flat.