Jump Start Question

I am a mechanical engineering student at the University of Cincinnati. I am currently working on a project and I need some help. I am designing and manufacturing an emergency jump start system, and I need to know EXACTLY how much power is needed to start a car. I know that I obviously need something close to 12V, but about how many amps? I have been looking over various information at great lengths but I am finding information varying from 200 amps all the way up to 1000 amps. Is there anyone with a very strong background in this area that can narrow down that range and answer this question for me? I would GREATLY appreciate it. Thanks for your time.

-Josh