This looks and sound great, but if you know the AI in this game, that should be flag, how horrible this can go wrong. And it does.
You get these scripted paths where you get randomly haul one of special cargoes. The simplest road is (on lane) the better. Moment you have to switch between lanes, your escort vehicles are erratic. Sometimes they switch no problem, sometimes they need a little extra help of yours to clear traffic out, so they can switch, sometimes they do not switch at their allotted path, so they suddenly stop. They suddenly stop because of traffic at other places as well, so be careful to not touch them, because that is mission over.
So highways are pain for AI lane switching as well as crawling 60 km/h on such a quality road.
Roundabouts - they kinda close them for you, but not completely. Escort vehicle waits until it is clear, then you can go. I once had a bus rounding around for a few minutes until I decided to reload (to clear traffic).
TLDR: The challenge is not to transport safely your load, the challenge is not to hit your stupid escorting AI vehicle.