https://imgur.com/gallery/dOxUEeR

Mammals make the largest group recorded, but probably not the largest group run over - mammals are simply easier to spot as they are large, and are probably likelier to motivate people to record their presence.

Records of invertebrates were largely uploaded by people moving on foot.

Reptiles probably make a large group of roadkill, because they are relatively slow moving, utilise road surfaces to warm up, are harder to see while driving, and may even intentionally be killed(1).

(1) https://www.tandfonline.com/doi/full/10.1080/10871200701322423 - Paul Ashley et al 2007 Incidence of Intentional Vehicle–Reptile Collisions