(1.) Regarding sakanas nefashos: driving, unlike firecrackers, is something that dosh bei rabbim.
(2.) There is a high risk of non-lethal injury, which brings up the issurim of chovel bachaveiro and bal tashchis d’gufo.
(3.) Pikuach nefesh and external damage aren’t the only factors here. Firecrackers cause hearing damage that can become permanent depending on the level of exposure. (Often people don’t even realize that their hearing is damaged until they take a hearing test. Or they might notice that they need to turn up the volume on the shiurim they listen to, or that they are more frequently asking people to speak up). In the unlikely scenario that the only person whose hearing is affected is the person making the noise, it is still assur because of bal tashchis d’gufo.