Check Engine Light On problems of the 2015 Subaru Crosstrek

I decided to drive from phoenix, az to san diego, CA when about 200 miles in, my engine completely shut off while I was driving about 85mph down the highway. The entire trip my car had been fine, the gas light had just come on about a minute before, but my car told me I had 50 miles until I ran out of gas. I had absolutely no warning of the engine about to shut off except that around the same time the gas light came on, my ac quit working. I was trying to mess with the ac when I suddenly went from 85 to 30mph and had to pull off immediately because I realized my engine had shut off. Once I pulled over and the car was completely stopped, the check engine light came on. I could not get the car restarted so I called a tow company to tow me to the nearest town. While waiting on the tow truck, I sat in my car using the battery to charge my phone, so I know the battery was not dead. Once the tow truck driver arrived he tried to start my car again, but could not. About 24 hours later I had a family friend come tow the car back to phoenix, and he was able to start the car and drive it onto the tow ramp! I was still afraid to drive it, and we towed it directly to the dealership. The dealership was able to drive it the next day, drove it for about 50 miles and said they could find nothing wrong with it. I have no idea what happened, but I'm scared to drive my car because if the engine would have shut off on a busy interstate I could have died. I had only owned the car for 10 days before this happened, and I hadn't even put 500 miles on it. Currently the dealership in phoenix has it and is trying to figure out what happened.