I wouldn't call myself a hypermiler, but my car is pretty efficient, and I don't drive like a dumb ass. I plan my braking and acceleration, I don't slow down for corners and only drive about 5-10 over the limit during my commute. (on weekends, I yolo my car to 15-20 over)
So I average about 5.5L/100km of 50/50 mixed city/highway.
I must say, I rarely touch my brakes. It's pretty easy to see when 3-5 cars in front of you, traffic is starting to slow. Just keep thinking ahead and not be so shortsighted, and you'll realize that you don't need to use your brakes a tenth of what the average person uses them. It not only saves your brake pad life, but you save gas by letting go of your throttle while everyone keeps accelerating to the inevitably slower traffic speeds.
It's not rocket science.
Often this.
It does, and no throttle = no fuel.