Don't be distracted by the EPA number, they probably just assigned the turbo mileage because the S was a late comer. I'm sure the S will prove out closer to the 300 mile mark and you can always drive like your grandma initially to hit that magic number once and then file it away! Is anyone...
Once it has been determined whether this is a sloppy under/oversight or a purposeful workaround to compensate for some compromised issue in the electrical system (cars seem to be stuck in port or at dealerships for a surprising long time for software updates), perhaps an engineering-pride type...