The 4g63t is one of the best engines ever made. This car makes over 275 horsepower, and gets an average of 21 miles to the gallon. Thats reasonable I think.
Other than that...eh, rating MPG on a car with a lot of horsepower is bullshit. You're going to drive it WOT a lot, so, gas mileage ratings dont mean shit when you have it floored.