You really need to get to know your route and your car to determine the "best" way to tackle hills. There are too many variables that could make any single method the best on a givin day. Certain techniques are always good but as conditions change you must change your method.

What changes? Same car, same hill right? Well not really. The wind and the charge in your pack can make a big difference in how you get over a hill. Traffic, stop lights and rain can affect the results as well. My HCH acts differently depending on how warm the engine is as well.

Examples:

1) I've got 2 similar hills to climb at the beginning of my commute. In the cold the car has not warmed up yet so I can get up the first hill in top gear with no assist if I take a running start at it, if the wind is not too strong in my face. The car is usually warmed up by the second hill and for some reason assist is more aggressive when the car is warmer. While the first hill is longer and steeper I have more trouble climbing the second hill. If the wind is blowing a downshift is required about half way up each hill to make it over.

2) I usually take most downhills with the engine off. If the hill is not steep enough to maintain speed ICE off with current wind situation the ICE must be kept on to add impulse to the system. If the hill is so steep that your speed increases over the limit the ICE must be on to use regen to slow the car down. Also if the pack is low I'll leave the car on to get some regen back in the packs.

3) Cresting hills is traffic dependant for me. Going to work there is more traffic so I crest hills faster so as not to slow anybody up. Coming home at night there is no traffic so I crest hills with just enough speed to make it over the top and the engine off.

4) If the pack is fully charged you might bang up a hill in top gear using a little assist to got over. If the pack is drained you might need to downshift to get upthe hill without assist. A downshift might also be required if it is raining, windy or if for some reason (traffic, stop light) you could not take a good running start at the hill.

Really long hills will drain a pack completely. There is only one such hill in my area and it caught me by surprize because the HCH can take all the other hillls in top gear no problem. I've only been over that hill once and it was quite a struggle once that pack was dead.