You don't have to drive like a granny to get good mpg!
Drive hard and try and reduce the amount of times yo use the brakes... You'll get good mpg this way! Of course this is easier said than done as it requires very long range vision and good planning!
And easy example I see everyday is people zooming past me towards a red light when I just roll the car to it. When the car is rolling in gear, it's using zero petrol as the ECU cuts out the petrol when the wheels are driving the engine.... This driver then has to brake to a stop and then get the car ,moving from a standstill on green (where it uses the most petrol). I can then just use very little throttle (say in 2nd or 3rd) to get back to 30 as quickly as possible, change to 4th and use about 5% throttle or less to maintain speed (and end up going past the guy thrashing his car to the lights anyway)
The gold standard to this is the police response units, who can drive through traffic from one side of the city to another without using their brakes at all! Of course they have the added advantage of lights and sirens but still impressive at the speeds they go at!
Oh, and I average 41mpg driving this way. Reckon I can get up to 44 / 45 if I get better at this!