Chinmay,
Try some smaller wheels and drop the bumper as low as you can get it. Geared correctly with the smaller wheels you will find the robot accelerates quickly. We design in the placement of the wheels close to the perimeter of the frame. The frame needs to be very stiff if you want the robot to run fast and turn gracefully. Try to keep the weight of the robot as low as possible and between the front and rear axles.
Here are some pictures of our 6 wheel sheetmetal chassis for 2012:
https://picasaweb.google.com/1177698...12BuildSeason#
One of 971 summer projects is to invite local teams to a question and answer to our design process, materials, fabrication methods. Shoot us a email if you are interested.
Roy