The six upgrade tracks in Star Wars Galactic Racer
Every vehicle in Star Wars Galactic Racer upgrades along the same six tracks. Turbojet Manifold raises Ramjet, Fuel Injector raises Afterburner, Repulsor Grip raises Cornering, Structural Bracing raises Resilience, Power Cell raises Battery, and Vector Servo raises the advanced stat of whichever class you are driving.
Each track runs from level 0 to level 10 and every level costs 1,000 credits, so taking one track to the top is 10,000 credits. Levels four and above can be bought as a faulty part for 500 credits instead, at the cost of carrying a Fault on the vehicle.
What each upgrade does in Star Wars Galactic Racer
Ramjet is the dangerous boost that overheats, so Turbojet Manifold is the track that rewards aggressive driving. Afterburner is the safe refilling boost, Cornering is grip, Resilience is how much collision damage you shrug off, and Battery is the energy that pays for your abilities. Vector Servo is the odd one out: it raises Kinetic Burst, Drift, Knife Edge or Air Brake depending on the class.
Upgrades are per vehicle, not per account, so a fully upgraded speeder bike does nothing for the landspeeder you switch to on the next planet.