Here are some fun and interesting things I found so far:

1. You can honk your horn three times at someone that's driving a sports car, and they will speed through the city like they are racing.  I like to follow them because it feels like a random street race.  Sometimes they go in a predetermind path around the city, so you can actually get infront of them without worrying they will drive somewhere else.  It's really fun and is has pretty cinematic moments if they end up crashing or the police start chasing them.

 

2. If you enter the cheat "Slidey Cars" (quickly press Y, RB(2), Left, RB, LB, RT, LB.) it makes it really easy to drift, and it feels really cool, so you can drift down the winding roads of Vinewood and Blaine County.

 

3.  If you sit still for long enough without touching the controller, a police chase will randomly start with a police car chasing an NPC controlled car.

 

4.  If you buy an expensive enough car, NPC's will compliment your car if yo are close enough to them.

 

 

Yatsukiii