[tzs]

Note that there are some types of accidents whose probability goes down the faster you go. An example would be getting hit head on by someone who veered out of the opposite lane into yours.

The probability of being in that kind of accident goes up as the number of cars that you pass in the opposite direction goes up.

Without loss of generality we can assume that there are no entrances or exits on the other lane between your starting point and ending point, because if there are we can simply treat you trip as a sum of separate trips between each pair of consecutive entrances/exits.

The number of cars you pass going the opposite way is the sum of the number that were on the road between your start and end point when you started and the number than enter the road while you are traveling.

The number already on the road does not depend on your speed. The number that enter while you are traveling does, going down the faster you travel.

Hence the faster you go the lower your chances of getting hit by a lane crosser.

[thfuran]

The closing speed between you and the swerver is almost certainly positively correlated with collision rate. Given that the base rate of even seeing someone swerve into opposing traffic is so low, I'd expect that effect to dominate. Even if not, severity of injury definitely strongly positively correlates with collision speed.

[hackernewds]

and also assumes reaction time speeds up proportionally with speed. it's the opposite