I used my own rain file for this low res animation plus a little warping to make it a bit more natural.
The splashes are actually a population of tiny little white grass clumps. The seed is animated so that each frame has a different seed. "Repopulate every frame" is checked.
I had to cheat a little bit: I used some frame blending in AE to make the appearance of the "splashes" look a bit less chaotic, and there's a bit of tinting the whole scene.
After I had finished the clip, I realized that each car I picked is blue. I didn't notice that before...