Do you actually need to lift the balls? If you can just push them around on the floor that might reduce the complexity of your design problem. If you have to pick them up, it may be easier to just use a shovel design like on the front of a backhoe. Then you don't have to worry about pinpointing their position and actuating a complex manipulator.
The more you can tell us about your project goals, the more we can help. Try to give us specific problems to solve. You are rather vague about the design constraints (size of robot, budget, environmental hazards, etc.). I also don't know what you mean by "in CAR's shape". Do you mean that you are building on the chassis of a full size car, or is there some robot named 'C.A.R.' that I am unaware of?
There is a section of this forum called Robot Videos (http://www.societyofrobots.com/robotforum/index.php?board=6.0
) that can also help you get inspiration for design ideas.
PS: I hope you have other people working on this with you. One person making a fully autonomous vehicle that localizes itself via GPS is a daunting task.