In the game, players take part in illegal street races that focus on different styles of races, utilizing a variety of licensed real-world cars (available at the time of the game's development and release) that can be upgraded and customized with new parts, while contending with the involvement of the police in their efforts to impede the player. Racing Events focus on competitive races with other drivers on circuits or point-to-point routes, checkpoint races, and races involving sprints or drifting (the latter being absent in its predecessor), with players able to use Nitrous Oxide and Speedbreaker whenever needed - either to help win races or get out of tight spots - both of which recharge over time. The game itself features four game modes - Career, Quick Race, Challenge Series, and Multiplayer - with the latter featuring online gameplay available in all console and PC versions of the game, except the Wii's edition.
The game operates on the same gameplay mechanics used in previous entries in the series, including its predecessor Most Wanted, though Carbon introduced new elements. A new element exclusive to Carbon are Canyon events - special racing events styled after Japanese Tōge racing, in which player compete in competitive racing on canyon roads outside the game's main setting. These events consist of sprints, drifting and duel events, in which the latter two feature a majority of destructible guardrails that the player must avoid crashing through or risk losing these respective events as a result. Duel events on these circuits operate differently to events involving major rival racers in Need for Speed games, as these are conducted across two stages on a canyon circuit - in each stage, one driver acts as the chaser and pursues the other at close proximity, with the first stage seeing the player as the chaser and scoring points the closer they can tail their opponent, while in the second stage their opponent becomes the chaser and the player must keep as much distance as possible to avoid losing too many points before the stage is completed. At the end of both stages the car who took the lead wins if their score is positive, otherwise their opponent wins if they turned it negative. Apart from scores, an instant win is possible depending on which mode the Duel is conducted in - in Career mode, the player can win instantly if they can stay ahead of their opponent for ten seconds, but lose if they fall behind for too long; in Online Multiplayer, a player wins if their opponent crashes through a guardrail.
Police pursuits, a staple of the series, function similar to Most Wanted in that police can turn up at any time during a race and attempt to impede the player during the event, except in Canyon Race events and checkpoint races; in Career mode, the police can also turn up during Free Roam, but will not act against the player unless they have a warrant (for evading a previous pursuit) or committed an offence in their sight, whereupon they focus on blocking in and arresting the player unless they can lose them and find a safe spot to hide until they lose their heat. As the player is pursued, they can either attempt to evade the cops, or knock them out of action by ramming their cars or using destructible props called Pursuit Breakers to impede their pursuit, though extensive pursuits will cause the player's heat level to rise, leading to stronger pursuit tactics including spike-strips, road blocks, and the involvement of state/federal authorities. Carbon modified the pursuit function by making police less dominant in arrest tactics at higher heat levels, and reducing the chance a Pursuit Breaker blocks/destroys a pursuing vehicle.
Licensed real-world cars used in the game are divided into three tiers (performance level) and three classes - Exotic, Tuner, and Muscle. For example a Nissan 240SX is a tier 1 tuner car, while a Corvette Z06 is a tier 3 muscle car. Cars receive visual damage during the game, but no physical damage. Cars can be upgraded in performance through new components and fine-tuning of each component - such upgrades can help, for example, to improve speed, or improve braking. Carbon added the ability to customize visual parts via autosculpt parts, which allow adjustments of components for example, while adding flexibility with vinyls and decals by allowing them to be placed in layers over each other, with the ability to modify these in shape and size, and place them anywhere on the car. Additional cars and customization parts can be acquired through completing Reward Cards - each card consists of a set of challenges for the player to complete across the game modes, and reward the player either with a new vehicle to use or new parts for customization.
Career Mode
The game's main mode focuses on the player competing in races against rival street racing crews, instead of individual racers like in Most Wanted and Underground 2. When starting in Career mode, players must choose a class that is not only permanent for their playthrough in this mode, but also dictates which of the initial three districts in the game's setting they begin in and which racing events are available first. Additional cars and classes become unlocked as the player progresses in this mode; any cars earned from Reward Cards for Quick Race mode are also available, but without limitation. Players operate their own crew in Career mode, and can recruit AI wingmen to assist them, each of whom operates under a different role - Blocker, Drafter, and Scout - and speciality - Fixer, Mechanic, and Fabricator. The type of role and speciality that each wingman operate under dictates how they assist the player - some can find shortcuts during races, while others can help to reduce police heat - with their role also dictating which car they drive in; the first two wingmen the player unlocks have their cars match the player's chosen class. During races, players may use their wingmen for a period of time, after which they must wait a while until their wingmen gauge has recharged before they can use them again.
To win career mode, players compete in races against other crews to secure territory - each district has a number of territories, each controlled either by the district's main crew or a minor crew through a series of racing events. Winning a majority of the races in a territory converts control to the player's crew and unlocks additional races elsewhere. Races that have been won can be engaged again, but the prize money offered is reduced as a result. Taking control of all territories will unlock a duel event with the main crew's boss, in which winning the event will allow the player to unlock special rewards, in a similar manner to the rewards offered in rival events in Most Wanted. As the player accumulates territories, they can lose any earned by losing control over its racing events to minor crews, either by failing to defeat them in takeover challenges or forfeiting the right to do so.
Quick Race, Challenge Series & Online Multiplayer
Quick Race mode allows players to create custom events for single player or multiplayer - both splitscreen or online - making use of any circuit and cars in the game, and altering various factors such as difficulty of opponents, track conditions and so forth; what cars and circuits can be used depends on the player's progress in Career mode, though all players can be allowed to use wingmen they have unlocked in these events, provided this option is allowed.
Challenge Series consists of a series of racing events that are divided into 12 categories, each divided further into three difficulty levels. Each challenge event requires the player to complete a specific goal, depending on the type of event, using a set car on a specific course in the game. Players may chose any category to begin with, unlike in Most Wanted, but must complete in order of Easy to Hard. Completing all of the difficulty levels of a challenge unlocks either a new car or customization option for the player to use in other modes.
Online Multiplayer mode focuses on two exclusive events for multiple players - Pursuit Knockout and Pursuit Tag:
In Pursuit Knockout, players compete in laps of a circuit, with each player in last place being knocked out and returning as cops to hinder the other players. The winner is the player who ends the race in first place.
In Pursuit Tag, one player is a racer and must evade the others, who operate as the cops. If the player is arrested by another, they switch roles. The winner is the player who spends the most time as the racer.
