How to edit dash cam video together smoothly?
Merely thinking about it in a logical fashion should lead you to the conclusion that what you want is not possible.
Beautiful or not, 3 hours is a very long time! Start by getting rid of the vast majority of the footage - more than a few seconds of a scene is intensely boring. Join the rest together with simple lap dissolves (the old scene fades out as the new one fades in).
You need to convert the footage to 16mm film, and then edit it on a flat bed editing table.