Have just looked up mileage figures and converted them both ways ( is US MPG the same as british MPG?)
In town, normal driving, I end up around 16.8 l/100 km, and when cruising along easy on a country road (driving 110 km/h or 68 mph), I get around 11.2 L/100...
This works out to 14 mpg in city, up to 21 mpg highway - in US MPG
Needless to say, driving 110 km/h in the S5 feels like the car is idling.....