Mod Suggestion.
Allowing a car seat in the car (Imagine that) so that a single parent can travel with a baby and a toddler.
Also, a Mod to force nonactive sims to purchase a car instead of taking taxies.
Create an actual dog door. I believe Sims2 had one.
Create racing poles for horses, so the horses and riders could race each other.
Add Drivers ED to all schools, and allow teens to earn their driving skill while at school.

Not sure if it's a mod I have or no, but my teens have been taking driving class at school for a while.

The quick reply will work just fine, or you can click 'go advanced' if you want to add pictures or links.