Upgrades

Upgrades can be used to alter any performance characteristic of a car. They are featured in every Forza main title.

By swapping stock parts with aftermarket upgrades, players can gain performance improvements and new performance index values. Many parts also allow custom calibrations by the player that can be performed at the Tuning menu.

In Forza Motorsport 7, players must comply with Homologation restrictions when upgrading their vehicle in order to compete in division-specific races.

Classes

Most upgrades are available in five classes and provide following performance improvements:

Stock - Original performance
Street - Mild increase of performance
Sport - Medium increase of performance
Race - Major increase of performance
Special:
- Drag - Performance optimized for drag racing (Motorsport series only)
- Hot Wheels - Performance optimized for track racing (Hot Wheels Expansion for Forza Horizon 3 only)
- Rally - Performance optimized for off-roading (Horizon series only)
- Remove - Remove engine restrictor to unfold power or remove rear wing to lose weight

Types

Players can choose from five upgrade types that have a great effect on certain performance aspects, although they can also overlap with other types in some aspects:

Engine and Power upgrades are essential for improving acceleration and top speed as they directly alter the maximum power and torque output of a car.
Platform and Handling upgrades primarily improve handling by reducing understeer or oversteer and shortening brake times. Each can be achieved by altering chassis and suspension components of a car.
Drivetrain upgrades consist of transmission and drivetrain upgrades, thus dictating the amount of power transferred from the engine to the wheels.
Tires and Rims upgrades refer to wheel modifications. Tire upgrades have a great impact on every performance field of a car as they determine how well the player's vehicle is able to transfer its power to the road. Players can also change their rims to reduce weight.
Aero and Appearance upgrades include aerodynamics alterations to a car and aftermarket body parts.
Conversion upgrades include major component replacements such as engine and drivetrain swaps. Installing a conversion upgrade can drastically change the driving characteristics of a car and may require additional upgrades from other types to counteract unwanted performance changes.

Immediate Upgrades

Players can immediately upgrade their vehicle to the limit of a performance class via the Quick Upgrade menu. This eliminates the necessity of having to install upgrades individually, although it is always possible to de-select a single or multiple parts generated by the menu before applying the upgrade.

In Forza Horizon 3, players can choose from upgrade presets which work similarly to Quick Upgrade but alter a car to achieve certain performance aspects for certain driving characteristics or raise a car to the maximum of a performance class. Upgrade presets are available for Horizon Edition cars and Upgrade Heroes cars.

Strategy

Cars are more effective for racing when upgraded to the maximum of a performance class, rather than being upgraded to the highest possible performance index value.
Tires are the most effective upgrades players can install as they affect every performance characteristic for most vehicles.
- In Forza Horizon 3, tire upgrades have a stronger effect on the performance index of a car than other upgrade types, making it possible to skip multiple performance classes even without installing other upgrades beforehand.
  - Players can take advantage of this aspect for drag racing by installing a high number of engine upgrades without switching to a new tire compound. This allows them to stay in lower performance classes which allows them to beat cars from higher classes with better tire compound but similar power, as lower class cars are allowed to launch earlier.
Differential upgrades may decrease performance index values due to adding weight even though they can be useful for reducing oversteer or understeer.

Discounts

Main article: Manufacturer Affinity

Main article: Forza Horizon/Discount Signs

Upgrade discounts are only featured in Forza Motorsport 2, Forza Motorsport 3, Forza Motorsport 4, Forza Horizon and Forza Horizon 3, although they are unlocked differently in each title:

In Forza Motorsport 2 and Forza Motorsport 3, certain upgrades can be discounted up to 50% for certain car brands.
Players in Forza Motorsport 4 are rewarded with a 100% discount after reaching Level 4 Affinity for a manufacturer.
Smashing a discount sign in Forza Horizon rewards the player a 1% discount. It is possible to smash up to 100 signs.
Forza Horizon 3 has a one-use perk that makes the player's next upgrade checkout completely free.

Notes

Reward cars in Forza Motorsport 4 come with upgrades as standard.
Quick-upgraded cars obtained from the Auction House can only be sold by removing their setup although this does not apply to Forza Horizon 3.
Opponents in singleplayer mode may use upgrades, sometimes exceeding the car's normal maximum rank.
Contrary to previous Forza titles, Forza Motorsport 7 does not have a shopping cart feature in the Upgrades menu that allowed players to choose multiple parts without having to buy them separately each time.