Thank you. You have helped me very much.
If I could ask one more thing, how do I go for searching "adding memory to my Arduino program" because only what I find is increasing its flash memory, which I don't believe that is what you mean.
The Arduino board is modified with more flash and an embedded "motor controlling Arduino shield".
If anyone wondered it is powered by 8 1,5V batteries and it has an aluminum chassis (I didn't have a say in this), to prevent the Arduino from killing itself it has a plastic sheet preventing it from touching the metal, I don't really know the RPM of the motors but I know they are powerful enough, two black & white sensors at the front and one in the center.
I will add the suggestions you have given me in this thread and hopefully well implement them. If I am able to finish this project, the end product will be here.