Actually, the turbo only uses the amount of fuel required to make the needed power, it's just a matter of efficiency. The turbo can make that power at a lower rpm (due to the boost) and there are less mechanical (friction) losses in the engine at lower rpm. In reality, the mileage should be pretty close.

Thats about all I ever got out of my SD, the SDL does a bit better but not by much.

The worst mileage I got last year in the SDL was 21.75. All around town, AC cranking, showing houses, and one brokers tour which just sucks the fuel since you drive kind of fast and have 4 people in the car.

Considering the size and age of these cars I think its excellent, at 560 would probably return 10-12 being driven like that.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200