Radial Tires

Upgrades

Basic tire, Bonus to Acc and Hndl.

Knobby Tires

Upgrades

Improves off-road driving

Studless Tires

Upgrades

Improves ice driving

Sports Tires

Upgrades

Increases Hndl, Acc and bonus to on-road

Hi Grip Tires

Upgrades

Increase Hndl

Slick Tries

Upgrades

Increase Hndl, Acc, On-rd, negative off-rd & icy

V6 Engine

Upgrades

Starter Engine

V8 Engine

Upgrades

Unlocks by upgrading V6 80%

V10 Engine

Upgrades

Unlocks by upgrading V8 80%

V12 Engine

Upgrades

Unlocks by upgrading V10 80%

Seamless Gear

Upgrades

Bonus Acc

Speed Gear

Upgrades

Bonus Speed, Negative Acc

Power Gear

Upgrades

Bonus Acc, Negative Speed

Hi Speed Gear

Upgrades

Large Bonus Speed, Negative Acc

32 Bit

Upgrades

Increase qualifying race bonus

64 Bit

Upgrades

Increase qualifying race bonus

Supercharger

Upgrades

Higher acc at low speeds

The best part you can carry over is the Supercharger, to get this part:
- 1st on the Dusty Plains Race so you unlock Dry Springs Sponsors
- Complete Dry Springs so you unlock Carbucks
- Complete Carbucks so you unlock Spongecorp
- Complete Spongecorp so you unlock Dull Comp
- Complete Dull Comp so you unlock Chimp Labs

Turbocharger

Upgrades

Higher acc at low speeds

Wing

Upgrades

Bonus Hndl, Negative Speed

Big Wing

Upgrades

Bonus Hndl, Negative Speed

Aero Body

Upgrades

Bonus Hnd and Dur

Lt Chassis

Upgrades

Bonus Spd and Dur

Carbon Chassis

Upgrades

Bonus Dur

Carbon Brakes

Upgrades

Braking increase

Gold Egg

Upgrades

Earn XP faster

Emblem

Upgrades

Improve ad revenue

Hyper Oil

Upgrades

Bonus Spd, Acc and Hndl

Coating

Upgrades

Bonus Dur

Tire Chains

Upgrades

Improves ice driving