because most of its body parts are made of metal sheet or plastic. Its has no ac in standard model,it has an engine of 624cc 2 cylinder,it has no ac,no power steering,bumpers are made of plastic and will give a max speed of 70 km/hr.
New Tata Nano with EasyShift is available at Rs. 2 lac (Ex-showroom, Delhi), and the final cost depends on the valuation of your car. So, first get the valuation of your car from authorized Tata dealer, so he can give you a final quote for the new car.