Automatic Hybrid Car System Design -- 2

I have a compact city-oriented car that I want to convert into a true hybrid: an internal-combustion engine takes care of propulsion while fuel is available, and the on-board battery pack must take over seamlessly as soon as the tank runs low... (Budget: ₹12500 - ₹37500 INR, Jobs: Arduino, Automotive Engineering, Control Engineering, Electrical Engineering, Electronics, Embedded Systems, PCB Layout, Product Design)