There are nine different upgrade areas for improving each vehicle. Here's an at-a-glance guide to what each one does - note that upgrades get more expensive as you continue through the upgrade chain.
Upgrade - Effect
Engine - Increases HP
Intake - Increases HP
Exhaust - Increases HP
Gearbox - Reduces shift time
Flywheel - Reduces shift time
Tires - Increases launch and drift quality
Body - Reduces weight
Nitrous - Increases boost duration
Suspension - Increases drift quality

Embark on an inspiring mission of human connection beyond the UCA. Sam — with companions by his side — sets out on a new journey to save humanity from extinction. Join them as they traverse a world beset by otherworldly enemies, obstacles and a haunting question: should we have connected?