2014 550i gas mileage

Can someone with a 550i tell me what is the typical miles per gallon on this vehicle. I got this car for my son four months ago and it seems like he’s only getting 12 miles per gallon. All of his trips are short like 4 miles each way. I do make sure he’s on Comfort mode. No lights are on in the vehicle and no gas smells. If this is the typical mileage, that’s fine but I just want to make sure nothing is wrong with the car.