ProMods

Is there a mod that allows you to sit on a passenger seat, while the AI drives the truck (or bus, car,..) for you?

If not, that would be really cool if it existed, usually you can't pay much attention to the scenery around you because you need to look at the road, but there's a lot of scenic roads that would be fun to ride through.

It's a good idea, but I don't think it's possible in ETS2.

As the developers said in one of their twitch streams, they did have ideas in this direction but decided not to add it in as they didn't want people to wander off map or walk all the way. So it is at this time impossible for mods to even start on this or something similar because the coding isn't there to start with. I personally would love to see it though, get out of your house, go to your truck, get in and drive off. But alas, it is likely not going to happen for years.