Upgrades are crucial for completing each of the levels and getting the best times to beat your friends. You can upgrade your truck in 4 different ways: Speed, Grip, Stability and Tilt.
Each upgrade affects the truck differently:
Speed - Improves power and speed
Grip - Better tires to climb hills with
Stability - Lowers the centre of gravity so your truck will be less likely to flip Tilt - How fast you can rotate your truck in the air
These attributes can typically be upgraded up to a maximum (this varies depending on the vehicle), once all of them have been upgraded to the maximum you can still collect <i>Truck Coins</i> for that truck which you can then spend on unlocking the next vehicle in your set.