I used to see around 17-18mpg as an average, going up to around 23-25mpg on an 80-ish motorway cruise. Foot-to-floor instant consumption would drop down to 2-3mpg. Once I did have her up to 28-29mpg with some seriously light-footed motorway driving; I was being very, very careful though! It should be noted that this was all trip computer figures, so could be inaccurate, though it wasn't far off judging by the amount of juice I was putting in the tank!