Upgrades can be used to alter any performance characteristic of a car.
Through the installation of upgrade parts, players can gain performance improvements and new performance index values. Some parts also allow custom player adjustments, which can be accessed in the Tuning menu.
Most upgrade parts are available in five classes and provide following performance improvements;
- Stock - Vehicle gains no performance increase.
- Street - Vehicle gains a mild performance increase.
- Sport - Vehicle gains a medium performance increase.
- Race - Vehicle gains a major performance increase.
- Rally - Vehicle gains a performance increase optimized for off-roading (Horizon series only)
- Remove - Only applies to Restrictor and Rear Wing upgrades.
Upgrades are categorized in six subgroups; Engine and Power, Platform and Handling, Drivetrain, Tires and Rims, Aero and Appearance, and Conversion.
Engine and PowerEdit
- "Engine upgrades can improve your car's acceleration and speed. You can add a more aggressive cam, stiffer valve springs, improve intake and exhaust systems, and a turbo or supercharger to get more power. Combine several engine upgrade types to get the most out of your engine. But remember: extra power alone won't win races. Winning performance calls for a balance between power and handling."
Engine and Power upgrades are vital for improving acceleration times and top speed, as they directly alter the maximum power and torque output of a car. Please note that some upgrades are not available for some cars.
Platform and HandlingEdit
- "Platform and handling upgrades include better brakes and suspension. Combine several platform and handling upgrade types to get the most out of your chassis. These upgrades result in better braking and cornering. But remember: race-winning performance calls for a balance between handling and power."
Platform and Handling upgrades are used for improving handling by reducing understeer or oversteer and shortening brake times. They can be gained by altering several chassis components such as the suspension and interior.
- Springs and Dampers
- Front Anti-roll Bars
- Rear Anti-roll Bars
- Chassis Reinforcement and Roll Cage
- Weight Reduction
- "Change how the engine's power reaches the wheels to improve your car's acceleration and speed. Upgrades to components such as the transmission, clutch, differentials, and driveline can improve shift time and allow you to fine-tune your gearing."
Drivetrain upgrades affect acceleration and top speed. Through fine-tuning of an adjustable drivetrain part, players can modify their car's performance characteristics on a larger scale.
Tires and RimsEdit
- "You can't transmit your car's power and handling potential to the road without the right tires and rims. The stock tires on your car limit track performance, no matter how you tweak your engine or suspension. Upgrading rims along with tire compound, size, and profile improves cornering and braking performance."
Tires and Rims 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.
Aero and AppearanceEdit
- "Weight and aerodynamic upgrades can improve your car's acceleration, speed, downforce, and cornering, but to get ahead on the race track you have to balance your upgrades. A lightweight, streamlined car that is short on power or handling won't win races."
Aero and Appearance upgrades consist of exterior modifications, which can be used to customize a car's appearance to the player's liking, to create more downforce to improve acceleration and handling and/or to increase top speed.
- "Change major components of your car, altering its very nature. Conversions affect the upgrades that are available in other categories."
Conversion upgrades include major component replacements such as engine swaps and turbocharger conversions. They can change the driving characteristics of a car drastically - players may need to install other upgrades to counteract any negative attributes such as excessive oversteer that were caused by a conversion.
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.
- Main article: Forza Motorsport 3/Car Level
- Main article: Forza Motorsport/Manufacturer Affinity
- Main article: Forza Horizon/Discount Signs
- In Forza Motorsport 2 and Forza Motorspot 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.
- Reward cars in every game are auto-upgraded through the Quick Upgrade option.
- Quick-upgraded cars obtained from the Auction House can only be sold by removing their setup.
- Opponents in singleplayer mode may use upgrades.
- Tires and Weight Reduction modifications are the most effective upgrades players can install as they affect every performance characteristic most of the time.
- Differential upgrades decrease performance index values even though they can be useful for reducing oversteer or understeer.