"Found a little bug in version in 1.0.0 0.18
The Map Cleanup feature ignores vehicles e.g. Cars, tanks and Spiderbot when they are in operation and travel further away. This makes exploring a bit difficult when it deletes multiple vehicles while exploring and a litte longer idling." - Casishur
From the Factorio mod portal:
"Found a little bug in version in 1.0.0 0.18 The Map Cleanup feature ignores vehicles e.g. Cars, tanks and Spiderbot when they are in operation and travel further away. This makes exploring a bit difficult when it deletes multiple vehicles while exploring and a litte longer idling." - Casishur