Big Green Bug

I have no idea what kind of bug this is. On our drive back to Utah we stopped at a gas station. I got out of the car to go in...the gas station was closed. I turned around and this guy was on the hood of the car. He was huge. I wish I could have put something next to him so you could see how big he is. Anyway, he stayed on the hood the entire time it took to drive to the next gas station. These pictures were taken at the 2nd gas station. I think we were in New Mexico.