engine stalled out at high rate of speed

Was traveling from NC to GA, Friday before Thanksgiving, to visit my daughter when going down hill at 75 miles per hour my RPM's suddenly shot up to 4500, check engine light came on and lost power. Was still able to brake safely and move to the shoulder, granted I was in the far left, high speed lane when this happened so had to stop on the left shoulder. Turned the car off for a while and then when I tried to re-start it it was running very rough and check engine light was still on. Called Subaru Roadside Assistance and 3 hours later towed to closest dealership in Charlotte, NC. Where I was refused a loaner car so had to have my daughter come pick me up.When they finally got around to looking at my car, the next Tuesday, I was informed by the service rep that I had run out of gas. I told him that wasn't true because according to the miles to empty reading I still had 70 miles to go. He said "no ma'am, you were out of gas". Rude jerk. Anyhow, he stated that they would have to put some gas in the vehicle to test it and that I would have to pay them for this gas when I picked up the car. Told them that was fine. They called back later and said they cannot find any problems with my car so it was because I had run out of gas. All readings on their little test machine were normal. When I picked up the car they were nice enough to comp the gas so I didn't have to pay for any of my troubles.