If you are interested in playing with some of the numbers:
Well, there is a nominal 47 miles available from the 17 kWh battery. You will be gaining, overall, 6000 feet. So, according to the laws of physics (and so far everything in the universe that we know of obeys the law of conservation of energy) you will be needing to expend an extra amount of energy equal to weight of car times vertical height foot pounds, which converts to about 9 or so kWh. A fully charged Clarity will start out with a bit more than 13. So, those up hill driving segments not balanced by downhill segments (probably in segments that will add up to about 12 miles) if using strictly battery, ie strictly EV, must eat up at least 53% or so of your battery capacity. And that assumes perfect energy conversion efficiency without considering heat dissipation and extra energy usage beyond the EPA's estimated values.
It would be nice to know that in HV mode the downhill gain in charge exactly balances the uphill gain in charge. Part of the considerations would depend I presume on how fast and smooth you drive up hill vs down hill. And doesnt consider the use of audio, heat, A/C, etc.