Cars are actually more aerodynamically shaped nowadays. But riding a motorcycle will give you the same result today as 20 years ago. To which I must say: yes, the insects seem to be back in larger numbers this year. At least in Germany.
But not everywhere: the less farm land, the more insects. Like, from literally none on farm land to "I have to completely clean my helmet because of all that yellow goo" in larger forests.
I haven't read the complete study but it appears that they only measured the impacts on the license plate? If so, this doesn't seem like good methodology because the license plate is only a very small part of the vehicle and position can vary wildly between brands and models. The license plate can be the most forward facing part but also be in a little cutout of the front fender.
It’s a great example of Scientisim and not Science. Of course the result confirms the popular narrative, so it will be cited without question. But the dead-obvious observation would be that by definition aerodynamic things tend to impact less, it’s literally what they’re designed to do.
But not everywhere: the less farm land, the more insects. Like, from literally none on farm land to "I have to completely clean my helmet because of all that yellow goo" in larger forests.