Crackdown Downloadable Content is sort of Free...and sort of costs

Free Downloadable Content
Keys to the City: The ultimate Cheat Mode! Enter this mirror of the main Campaign for a clean-slate game that can be fully exploited and customized for a single play session. (Note: Achievements and leaderboards will be disabled in this mode)
Build a pile of 100 explosive drums at the top of the Agency Towwer -- then let rip!
Spawn a ramp truck anywhere and it'll stay there
Create an agency vehicle or one of the new Peacekeeper vehicles any time, any place
Players can set character skills however they want them, or just activate the accelerated skill leveling feature (Crackdown demo anyone?)
Check out Super Agent Agility to jump ridiculous distances, swim faster than a torpedo and sprint faster than a speeding bullet (almost)
Try the Super Agent Strength to toss a truck with deadly accuracy further than ever dreamt. Boot enemies into the stratosphere!
Get the most out of the exciting selection of new weaponry by activating infinite ammo. Max out the selection at each supply point too!
Do all of this without skipping a beat of the action -- the pop-up cheat menu is always available during play without pausing the game
Vehicle Impounding: The Agency Garage has been given an overhaul; this was partly to accommodate the brand new Peacekeeper Vehicles, but also to allow Agents to impound their favorites so that they're always available&in their preferred color.
Impounding is simple: commandeer the vehicle and return it to the garage
Vehicles that aren't yet impounded are displayed as feint images, so players can see at a glance what's missing from their collection
The 'Confiscator' achievement awaits those who simply had to catch 'em all
Co-op Trophy sequences: A trophy emblazoned with my gamertag displayed for me and my opponent every time I win at the existing mini-games? Yes please!
Psychotic Mission Trials
A record is now kept of Time Trials completed at 'Psychotic' difficulty
Scoring the maximum 21/21 isn't just the ultimate challenge that every true Agent of Justice should have the stones to take on, but it's also the only way to unlock the highly coveted "Psych Out" Achievement
Premium Downloadable Content New Vehicles:
Agency Patrol Buggy:
Double wishbone suspension absorbs the bumps in spectacular fashion
Rides over anything - even when scaling near vertical surfaces
Insane air control
Roof mounted, independently aiming mini-gun activated with either "B" or "Left Bumper"
Agency Pursuit Vehicle:
Ridiculously powerful mono-cockpit race car
Acceleration that blows away everything else in the city
Incredible grip and top speed
Those road race leaderboard times are set to tumble!
Agency Armored Vehicle:
Like the Agency Truck, the AV can smash through barricades with ease
Tank like in design, occupants are completely protected from assault
Surprisingly fast and agile for its size
Rockets fired from independently aiming main turret with either "B" or "Left Bumper"
Street Racing: Pacific City is finally free from crime. Agency activity is once again concealed behind closed doors. The remaining peacekeepers, having very little to do, quickly grew restless. To satisfy their lingering lust for danger, high risk Street Racing tournaments have been established across the city.
Compete in 6 different on and off road races across the city
6 radically different vehicle options per circuit
Race against up to 11 other 'do or die' opponents, including another player over XBL
Compare fastest race times as well as race wins for that session with your co-op "buddy"
Players can post their fastest time per circuit to the online leaderboards
Take advantage of the world of Crackdown to win by any means necessary: create road blocks, hit gas tanks, or simply slam opponents into submission
New Equipment MSK Lobber
Mini rockets are thrown out from the rotating muzzle section before their boosters ignite and swarm towards their target.
The homing mini-rockets are incredibly agile making this the ultimate fire-and-forget weapon
EX1 'Proximity Charge'
Similar to the standard issue "Limpet Charge," these can be attached to any surface.
A visible local field is generated when the charge is set. Enemy penetration of this field will result in detonation.
In a bid to reduce the extensive civilian casualties lying in the wake of any crime fighting Agent, intelligent threat-sensing technology prevents the charge from detonating when a firearm is not detected
Unfortunately the technology isn't quite intelligent enough to prevent detonation due to field penetration by another Agent
HRX 'Harpoon'
A powerful gas powered mechanism capable of launching a deadly, razor-sharp spear over large distances with incredible accuracy
Can be used to ensure enemies "stick around" when players need them to, or to attach perps to their vehicle if they need to take them downtown&or around town
MZ360 'Mini-Gun'
The ultimate fast-firing projectile weapon
"Spin-up" to full fire rate takes some time, but then the devastation is incredible
Comes with a bountiful supply of high-caliber ammunition
VS1 'Cloaking Device'
The perfect device for the Agent that likes his action served psychotic, or for anyone that just needs to get under the radar from time to time
Renders the player barely visible and off radar
The VS1 is fuelled by Agency suit armor; when depleted an Agent can find themselves distressingly vulnerable
New Game Types Max-Agility Rooftop Races
Compete solo or with two players in races across the city rooftops
Nine new races in total, each with its own solo & co-op leaderboards
Four are with Los Muertos, three with The Volk, and The Shai-Gen play host to the remaining two
And no, gamers won't need to complete these too for the existing "Over Our Heads" Achievement! Stockpile
Each district (including Agency Island) hosts a Stockpile game - clearly identified with its unique beacon
Stockpile can be played solo or in co-op
The aim is to collect all the game specific orbs (also marked on the tracker) in the fastest time
Best times are uploaded to the online leaderboards
Two players can work co-operatively to find all the orbs in the fastest possible time, or simply compete for the highest score when the time runs out
In the case of competitive play, it doesn't always pay to do the grunt work of collection; when an Agent is killed he drops a third of his spoils
Checkpoint Chase
A highly addictive two-player competitive game that makes the very most of the world of "Crackdown"
The game can only be initiated in one place - the Agency Garage
A random target destination is identified somewhere on the city, but is only marked on the tracker (not the map)
The first person to reach the destination gains a point and activates the next checkpoint
The winner is the first to 10 points
Other than that, Checkpoint Chase has no rules!
Rocket Tag
The ultimate competitive combat event!
Each of the 21 gang boss lairs now also plays host to a game of Rocket Tag
When the game is activated the players are randomly assigned as "hunter" and "hunted"
The hunter has a straight-shootin' "Hotshot" rocket launcher and more ammo than he could ever need!
The hunted has a pistol
To win, the hunted player must avoid being caught in the blast of the rocket launcher for 60 seconds. Simple!
Achievements: The new content brings with it seven new achievements (taking the overall total to a nice round 50). Let's get one thing straight, nobody's paying for the 100 points that were missing from the original game - and in fact we're repaying that debt with some serious interest! In total the download pack unlocks a whopping 350 gamerscore!
Confiscator *
Impound all the chosen vehicles and store them in the Agency Garage
40 Gamerscore
Psych Out *
Complete all Time Trial missions at the Psychotic Difficulty level
100 Gamerscore
Stockpile Supreme **
Complete any Stockpile mini-game in less than 2 minutes and 30 seconds.
10 Gamerscore
Flippin' Crazy **
Complete 3 flips of any type in a single jump in any vehicle
20 Gamerscore
Body Armor **
Use the Harpoon gun to attach 5 corpses to a single vehicle
10 Gamerscore Street Racer ***
Win all Street Races using any vehicle
20 Gamerscore
Street Racer Elite ***
Win all Street Races using all available vehicles
150 Gamerscore
* Available with Free DLC** Available when one player has Premium DLC*** Available only with Premium DLC