Last night I got stuck in a situation where I was at a gas station in the middle of nowhere with a car that requires premium fuel. Since I was not sure if I’d make it to the next stop I opted to refuel with the regular fuel. So I put in 5 gallons and got back on the highway.
When I got to a station with premium I filled the tank up all the way. Did I just do damage to my car?
You should be fine, 5 gallons of regular + 10 or more gallons of premium, no problem. And the E320 is not turbocharged. I wouldn’t give it a second thought.