Have you tried Hero Express yet? 
If so you probably know the game power-ups, but let's introduce them anyway.

The Jumper, a powerup that allows the player to jump and avoid death, surpass obstacles, or reach otherwise unaccessible areas.
Also in some tracks it's a necessary power-up to progress through the track.
Here in the GIF you can see an example of a jumper used wrong as the car's speed was almost null when used.

To talk about the Cleaner we have to first talk about objects that soil your car first.  These objects (that are different for every track) will dirty your screen while making your wheels slippery.
This is obviously a pain while trying to climb hills and rush to the next gasoline.  The Cleaner allows the player to clean the dirt, getting things back to normal while playing a cool effect.
The effect was made using a normal map to distort the image to simulate a watery effect.

What do you think about that?