Driving a truck is different from driving any other vehicle. It is tougher because it is harder to maneuver. Most of the time, you would carry some cargo, so you need a trailer attach at the back and that is something that you won't see in any other vehicles. If you see most of the driver of a truck, you would notice that they are bigger. This could be because trucks are hard to maneuver and they would need the strength to do it. Driving all day is tiring and if you don't have the stamina then you couldn't expect to last that long.
In this case, you would not drive an ordinary truck, but a truck that got a jelly for its wheels. If you think that driving a truck is already tough then this game would challenge you even further as it is harder to control than just a truck. The idea here is to reach the finish line. Grab some coins as you go on your way. Try not to lose the coins that you gather. You need to save it till you reach the finish line. That is a challenge that you need to overcome to get to the next stage.