Get Outta My DreamsG 30

To unlock this achievement you simply need to kill one of each of the five freak zombie types with a vehicle. Freak zombies can be encountered randomly and appear as larger blips on your hud map in the bottom left corner of your screen. You can also locate them by climbing any high structures to survey the surround area or may very well be given a mission to specifically kill one of them. Here is a list of the freak zombie types in least to most dangerous order and how to kill them:

1) Screamer Zombie - These armless zombies scream to alert nearby zombies. If you get too close their screams will also prevent you from fighting or running away. Their screams should not effect you while you are in your vehicle and will quickly when struck by your vehicle

2) Swat Zombie - These zombies are dressed in riot gear and can not be killed with bullets. These zombies are also

3) Bloater Zombie - These zombies are more rare then others and are filled with putrid gasses. Killing them will unleash a gas cloud that will cause you to lose heath and stamina where they died. You run one over with your vehicle, but it will become a coffin if you stay inside it as all the Bloaters guts will have coated the vehicle. The gasses will eventually dissipate so you will be able to get back into the vehicle are some time passes.

4) Feral Zombie - These zombies are very dangerous and will kill you very quickly if you are not in your vehicle, they can sometimes take you by complete surprise because they are very quick. Their skin is a yellowish hue, they move on all fours, and have an amazing leaping ability. Because they are incredibly nimble, it is very difficult to run them over with your vehicle in an open area, but you can get lucky. A good place to kill them is near some form of wall. They will jump into it to dodge your vehicle and if you are quick enough you can pin them for the kill.

4) Juggernaut Zombie - These zombies are huge (they remind me of the wrestler King Kong Bundy) and dangerous for a few reasons. Even for their size they can charge at you fairly quickly. They will severely damage your vehicle if you try to use it to kill them. It will take a lot of damage to bring one of these zombies down. Since you must kill this zombie type with a vehicle it will be best to soften them up with firearms and then use a vehicle that you do not plan on keeping to kill it. Even then your vehicle will never be the same.

Also to remember, backing up over enemies or open door kills won't cause damage to your vehicle, in case you don't have a mechanic in your community or facility built. Running over enemies head on will cause damage to your vehicle.
4 out 5 of the freak zombie types can be killed easily by running over them just once with a vehicle. Juggernauts can be a little more difficult. The achievement did not unlock for me ehen making the kill just by ramming into him several times. I had to actually run him over once he was down for it to unlock. So knock him down then quickly run him over to make the killYou'll want to be driving a truck, even better a military truck, or at least a SUV. Juggernauts are tough and driving a vehicle will grab the attention of nearby zombies so using a coupe or sedan will break down completely pretty quickly when taking one on which will leave you exposed and possibly torn to shreds if there isn't another vehicle nearby to escape in. Running into juggernauts will completely destroy your front or rear tires depending on which way you run them over, so it's best to back over them over if you can so you can still escape afterwards.