Americans; I am trying to understand the subtlety and nuance of your expression “to haul ass”.
Does it mean “to hurry”? Or more “to move under strain”?
Or something else?
It means ‘to be putting lots of effort into moving fast’. Often with a connotation of doing so to an irresponsible extreme.
It means to move with all possible haste.
It seems like others have already given the definition, but I do want to introduce you to the wonderful thing that is Wiktionary.

https://en.wiktionary.org/wiki/haul_ass
It’s part of the same project as Wikipedia, and it has a very comprehensive compendium of definitions for slang terms.
Urban dictionary for academics
Urban Dictionary for people who actually want to know what words mean
Awesome, I didn’t know it know had slang 👍
In my opinion Wiktionary is probably the best English dictionary on the planet and probably the best English to other language dictionary as well.
Some additional nuance that I didn’t see yet: there’s a specific meaning to the command or the future tense of hauling ass, as that usage tends to imply the need for haste, specifically to hurry, e.g., “we gotta haul ass”. However, in the past or subjunctive tense, it tends to mean great speed without necessarily implying anxiety or haste - the speed could be entirely innate and casual - e.g., “they were really hauling ass” or “this thing can really haul ass”.
To me it means to move quickly. Often it means to move quickly under strain, but not necessarily.
(Moving slowly under strain is not hauling ass.)
The best example I can think of would be the insane running animations of Peppino from Pizza Tower:


And this scene from Rat Race (2001) is maybe less helpful but still relevant: https://youtu.be/PzjLImF8Zbc?t=1m5s
In my mind, hauling ass means to go as fast as possible, generally dangerously so. There usually is a solid reason for it, like escaping something, making it somewhere on time when you’re already late. I’d say it’s under strain, but the strain isn’t that you’re carrying a load, it’s that you’re pushing your vehicle or yourself to its limits, or perhaps beyond them.
It’s an urgent “hurry” maybe similar to “careening”
TIL!
Careening specifically implies having little control while going fast. Hauling ass doesn’t suggest lack of control.
It means all of the above, but the typical usage is to go really fast.
I have used that saying to mean time to leave.
Go fast or hurry up.
To hurry or leave.
But my mental picture is a donkey in a trailer…
I feel like in addition to what was said, something or someone which is “hauling ass” seems to tend to be on the larger side categorically? A person who carries a lot of momentum when running (not just cuz they’re fat but could also be with a big pack on) or a larger or louder vehicle. It feels like it comes with an implied “caution!” And not necessarily just because they’re not being cautious as others have said.
It means ‘to hurry.’
Going fast.
It’s more like “escape” or “leave suddenly”.
Nah, you can also be ‘hauling ass’ toward something. Or even just in general, with no specific destination or origin.
toward
Sure, but it’s usually refuge: Hauling ass towards the border, hauled ass all the way home








