Potential Energy = mass * g * height.
So, for example, for a 1,000 foot climb in a 3,500 lbs LEAF (estimate; incl. 1 driver),
PE used = (3,500*0.454) [kg] * 9.8 [m/s/s] * 304.8 [m] ==> [kg*m*m/s/s] =[Joules]
1 Joule = 1 Watt * Second
PE = 1,589 * 9.8 * 304.8 = 4,746,407 [Joules] ==> 4,746,407 / 3.600 [Wh] = 1.3 kWh.
So ... IN ADDITION to whatever driving distance you complete (as if you are on flat ground, for example 250Wh/mile), you also spend 1.3 kWh to climb 1,000 feet. If the regen is totally efficient (and the LEAF's charger let's you) you can gain all of that potential energy back on the downhill. (The level of incline on the rise does not matter so long as the car can handle it. On the descent it depends on the firmware allowing regen or coasting if you can. If you need to use the friction brakes you're wasting the Potential Energy.)
Hope this helps