Fun concept but there are two core competing mechanics. The level design + racing game feel makes the player want to go as fast as possible, but the point system being based on killing people rewards moving much more slowly. I think to really hone in on the concept of roadkill killing people, you have to either take the setting away from a racing track or reward both moving fast & killing people (maybe a multiplier based on how far you send a person flying)

It's a fun idea, but I can't help but feel with this theme, it would be better if you were a big moose or deer or possum or something that gets roadkilled, and charged into people in their cars. I say this because apparently, animals don't always make the best drivers 😄