I'm not sure this is true. I've been told that, for example, the "city" MPG of hybrid cars with regenerative braking is higher than the "highway" MPG. This is

I'm not sure this is true. I've been told that, for example, the "city" MPG of hybrid cars with regenerative braking is higher than the "highway" MPG. This is because it simply costs energy to maintain speed in the face of hills, wind resistance, and parasitic/rolling losses. However in "city" driving much of the energy is reclaimed through braking. A big part of this is wind resistance; as you know wind resistance increases with the square of the speed, so going 60MPH is going to cost quadruple what it costs to go 30MPH, and presumably "city" driving doesn't go much higher than 30 MPH.