To get this you either need to be the pilot of a Vehicle or a Passenger road kill does count
Also I can confirm that even kill streaks count as long as you are driving or the passenger
RCXD kills count as you are the driver
Chopper Gunner counts as you are the passenger
When I got this I had 49 kills from a vehicle (weapons hot medal)
21 RCXD kills
30 Chopper gunner kills
I found this out by accident as I was taking a break from fire team and got it while being a chopper gunner which I got from a care package.
Just be patient and have fun. This is easiest and fastest in fireteam with the vehicles but can be done playing normally.