one environment guaranteed to put stress on any car: the German Autobahn
Have you ever actually driven on the German Autobahn? It is probably the most simple environment for an autonomous car, because absolutely everything is very clearly defined and built to standards. You have very reliable road quality, width, signaling. No traffic lights, roundabouts or intersections. Very few traffic rules (basically speed limit and whether or not trucks are allowed to overtake on this stretch). Construction sites are about the only tricky spots you will ever encounter. Even incoming and exiting traffic is very simple to handle, because there is one and only one way in which it will ever happen.
If I were to write autonomous driving software, I would start with the Autobahn, and then go to more complicated road systems later.
For trucks, even speed is trivial. The general high speed of trucks is 80 km/h, so if you are a truck you stay on the right lane and stick to that speed and that's it.
Left-lane driving on the Autobahn is more interesting, especially for foreigners (you think you're going crazy fast in your rental car at 190 km/h (about 120 mph), and there's this BMW behind you signaling to get your slow ass out of the way). But we're talking about trucks here.