Constructors Constructors: These are your settlers, they can improve the buildings (terrain) around you and construct new highways. They are also good at founding new Police Departments. They have no combat capabilities.
Deputy Deputy: The deputy is one of your first advances in the policing field and can be a very useful unit. The deputy is good on attack and defense but slow, with ADM (AttackDefenseMovement) of 4,3,1. No, he is not an angel but in this guide he is bathed in blue light so you can see him better :)
Private Private: The private is your starting defensive unit. With an ADM of 1,4,1 that makes it solely for station defense. You could also block off some key bridges with this unit to keep parts of the city safe from takeovers in the beginning.
Lieutenant Lieutenant: The Lieutenant is your cheapest attacker in the beginning of the game with an ADM of 3,2,1 making him slow but effective in taking and holding ground from lighter units. For faster attacks I would recommend using the Patrol Car because it packs a punch but with speed.
S.W.A.T. S.W.A.T.: Special Weapons Assault Team, they're expensive but well worth the cost. A couple S.W.A.T.s can whack any defense that the scum of the city might try to present. With an ADM of 9,4,3 they are the most powerful conventional land unit in the game--a huge advantage for the police early on.
Helicopter Helicopter: Fast and lethal these bad boys are the aerial police units with the punch, but their only weakness is that they can't defend at all. An ADM of 6,1,16 makes this unit the fastest in the game.
Bombsquad Bombsquad: These units are fast and ferious with an ADM of 6,1,4. Responding to bombing cases has left them with the ability to get to an area quickly and neutralize it.
Patrol Boat Patrol Boat: The Patrol Boat is your first naval weapon in the game and can achieve naval superiority early in the game. With an ADM of 4,3,8 it can scim the large rivers of your city for criminal scum.
Cutter Cutter: As soon as city council gives you the ok to buy equipment from the Coast Guard, you can buy this lovely ship and use it to bombard the criminal element of your city. The ADM of 6,4,12 leaves this craft speedy and powerful. More than enough force to cripple even the biggest of criminal moguls.
Squadcar Squadcar: Once you attain the approval to add these to your arsenal, you can ruin the whole criminal world around you. The ADM of 6,3,3 allows this unit to efectively police large areas of your city and root out the criminal element while defending civilians from attack.

Patrol Car
Patrol Car: The patrol car gives the police the speed avantage early in the beginning by allowing the police to make quick attacks throughout the city. With an ADM of 2,3,8 the patrol car is certainly not the most powerful unit but the speed at which it can respond is incredible.