Late 30s, early 40s is easily achievable with early gear shifts to keep out of boost, and low cruising speeds, but that's dull!
The real measure of a car's fuel economy is it's long term average. Not short term anomalies.
Driving normally, i.e. regularly boosting, cruising at 80+, heavy traffic etc, mine has averaged 33mpg over the 8 years I've had it, which is right about where it should be for the engine's power, vehicle weight, and gearing