I would recommend against using Simple Green undiluted. I used it on my truck's dashboard diluted about 1/3 SG to 2/3 water, sprayed it on and let site for about 2 minutes (the dash was filthy with heavy dust from 4 days of dirt and trail driving) and it ate away the dash pad vinyl covering in the crevice where the airbag panel is. It only damaged a spot about 3/8 of an inch long but still, I didn't expect it to do that. The directions say dilute 20:1 for general cleaning. I would follow that mix to be safe.
Just my .02