Commercial trucks in the US are required to have something called an electronic logging device (ELD) to track driving hours, log engine data, etc. Some ELDs have some kind of remote code execution vulnerability. The second paragraph of that article talks about taking control of a truck, which sounds like a gross overstatement. Later in the article it says that this could allow an attacker to force a truck to pull over.
This vulnerability is said to be exploitable via WiFi or bluetooth, meaning that you could potentially do this if you’re on the road near a vehicle with a vulnerable ELD. The article also says that an attacker could upload an exploit to a vulnerable truck in a way that the exploit could be self-propagating.
The effect of this is probably limited to a small number of trucks. But if a particular company had bought a bunch of trucks with this problem, and if the company were reliant on the trucks for its revenue, a character in your story could use something like this to cripple the company’s fleet. Your character could remotely upload a self-propagating exploit to one truck, and then that truck might spread it to others back at the company’s warehouse. Imagine what that could do to a small company.