@jaswant135 - there are many possible answers to your ?n. As an example, you could take an old RC car, re-purpose its chasis, motor, servos, etc and have them all be driven using components that can drive them - all under the "command" of the Arduino.
I am currently working on a project that uses an old RC car chasis (http://alibe.codeplex.com/
). It's a chasis from an old radioshack "Pro-Pulse" rc car. Works pretty good once you get it all figured out. BTW, you might want some hot-glue sticks and hot-glue gun
Arduino is probably the best routes to take (IMHO) as it gives you the end-end options. You can start small and go anywhere. Search the forum for Arduino in satellites. sky is literally the limit.