Porsche 911 Carrera 4, Carrera 4S 991 EPA Numbers Surface
The 911 Carrera 4 will return 20 mpg in the city and 28 mpg on the highway, when using Porsche’s PDK double clutch gearbox, while if you opt for the seven-speed manual gearbox, you’ll only lose 1 mpg (this is true for both numbers). If you want to let the wind run through your hair in the Cabrio model, you will see the highway mileage dropping to 27 mpg (26 mpg for the manual).
As for the 911 Carrera 4S, this will return 19 mpg on urban roads and 26 mph on the highway. Again, these are the figures for the double clutch gearbox. The manual leaves the highway mpg untouched, while reducing the city one by a single mpg.