How about stats that upgrade with experience? After you have bought all the upgrades and bonuses, that's all you can do. But if you got upgrades over time, it would encourage you to play more even after you've bought everything.
Trying to give constructive criticism:
I do like the little detail of how the bananas appear in the back of the truck when you pick them up. You should get points for doing flips/tricks. Maybe add other trucks to race with. Points off for possible copyright infringement. With some work, this could be a fun game.
I really like the concept. I think with some great background artwork and some more variety in the gameplay, (monsters, puzzles, etc.) you could have a great game.
 "Second Person Shooter"){kind=icon}
 "Learn to Fly 2"){kind=icon}
 "GemCraft Labyrinth"){kind=icon}
 "Donkey Kong Truck"){kind=icon}
 "Castle Wars 2"){kind=icon}
 "Mushroom Revolution"){kind=icon}
 "Escape the room"){kind=icon}
 "Gorillas.bas"){kind=icon}
 "Space Station Jason"){kind=icon}