When friendly fire is turned off on free mode and you shoot a car with a rocket launcher that has more than 1 person inside it lets you kill the passengers, but the driver will just get out. I havent searched to see if this has been posted already and i think it's in right section.

It's because the car blows up and kills the passenger and gives you the kill. I've seen it loads.

I know, i was wondering if it's considered a glitch since friendly fire is turned off.

It kinda depends... You can do it with a bike to :P except when someones on the back of your bike if you wheelie to far back it crushes them giving you the kill or vice versa.