I saw a marmot on the way back from church, straddled it, and pulled off the road. Several people swerved around it as I was taking pictures; one even waited for an oncoming car to go past, then swerved around it. I’ve observed marmots, opossums, and a raccoon (which doesn’t count since it was at the edge), and only about 1/6 of passersby straddled the animal. The rest swerved. Why? They weren’t driving steamrollers!
Many vehicles are pretty low to the ground, and might have components underneath that hang slightly lower than the body. If you don’t quite clear the animal, it could crack the plastic bumper/trim or worse. That’s a couple thousand dollars to repair, assuming there was no other damage.
I have a truck with a slight lift, enough for me to crawl under without jacking it up. I just drive over roadkill.
Because they don’t want dead animal bits on thier car I assume. I know that’s why I’ll swerve around roadkill (plus it’s ingrained in me from a lot of road cruising for snakes-swerving is less likely to go wrong)
I would guess that it just has to do with human image recognition and reflexes. People see that there’s something in the road before they know it is roadkill specifically. Their initial reactions/reflexes are going to be based on the perception of something being there and not being sure exactly how big it is, whether it is hard or soft, etc. The most basic instinct for most people with imperfect information is probably to go around (safer option assuming road conditions are good and no oncoming traffic). If they have time to assess size/identity more or recognize the roadkill quickly, then they might go over it once their brain has assessed that this is a safe option.
I think it really boils down to whether or not an individual can smell (and is bothered by the smell of) decaying flesh and wether or not they’re willing to try to clean it out of the underside of their car. Some people legit don’t even notice the smell, but most people do so that’s why you see so many people swerving
In Alabama, I saw more than one driver aim for a box turtle that was trying to cross the road … once when I was walking back from my parked car to rescue one. So, it depends.
That’s pretty sick.
While most people only care about the dead animal bits on their car, I’m sure some people do it out of respect, as to not run over the animal that already didn’t deserve to die.
i try not to hit anything in the road, tbf
and carrion tends to attract insects, so the marmot may be dead but the numerous beetles and flies etc. are not!
Yes, unless I feel confident I can straddle the animal–I want to try to avoid mangling its corpse further.
Unfortunately, research indicates that between 2% and 6% of drivers will deliberately go out of their way to run over animals on the road :(
We were at the entrance to Rocher Pan nature reserve. Before we could even think about rescue a ‘passing’ car splatted a tortoise. Still torn between horror and fury all these years later.
Someone needs to tie these people in the middle of a road and let them feel what an animal feels when some car is bearing down on them on the road…not that I’m blood thirsty or anything. Maybe the car will swerve away at the last moment 94% of the time..ya never know 
Lots of reasons. I swerve for cloth and cardboard boxes, too. I don’t know if something in there would harm my car (or something I would regret flattening). Straddling the thing in the road may work, but that’s often hard to judge in the seconds I have to decide. Also, in the instant I have to decide, I often can’t be sure the animal is dead. And I hate to further mangle dead things. And I dislike the smell of skunk or of rotting things if they get on the car. And I’d like to photo the thing for iNaturalist if I can – flattening it further won’t help that goal.
One day I straddled a live bullfrog in the middle of the lane and it jumped up as I passed, hitting its head fatally on the car. (I know because I pulled over and went back to photo it.) And one day I was in a row of cars, possibly driving a little closer than I should have, and I found myself driving over a dead deer, straddling the head. It bounced “Thunka thunka thunka thunka” down the length of my car. Disgusting memory even now. I’ll swerve around dead things (or living things) if I can.