I know how you feel.  I lost my good hunting buddy to someone speeding down our gravel rode only this person swerved INTO my driveway to hit him.  He was a good 10 feet off the edge of the road and I witnessed it.  I never saw the car again but we deal with speeders all the time.  Slowing down by a farmyard or house should be common sense but most people don't realize it or do it.  I'm sorry about your cat and especially with how much the cat brought comfort during your families' trying times.