Travel.SE has quite a few questions about road rules (example search), but many of them have been closed or have close-votes because they are "not about travel".
Are these kinds of questions on topic on Travel.SE?
If the questions relate to travel, I'm good with them being asked and answered here.
Some of these questions could be:
I've asked a question on Travel.SE about US tolls, which I think was perfectly on the mark. The traveler consideration for paying tolls is quite different than that of a permanent resident of a jurisdiction.
What is on-topic are questions about car travel, e.g.
I e.g. wrote some answers about German autobahn or traveling in Italy.
What we don't want here are answers about single situations which are much too special for an answer and are of very limited use for further users.
One of the closed question is asking if you should use the left or the right lane without markings when driving straight. This question could be right out of a driving license test and if a question resembles that, it is off-topic.