You cannot actually select EV mode. Press the ECON button to activate ECON Mode, which keeps the Clarity in EV Drive more easily than NORMAL Mode or SPORT Mode. In ECON Mode, the accelerator pedal "click" separates EV Drive (battery-only) from Hybrid Drive (battery + engine). The Clarity will stay in ECON Mode when you restart the car.
Pressing the ECON button a second time turns off the ECON icon and puts the Clarity in NORMAL Mode. NORMAL Mode remaps the accelerator pedal response to provide more acceleration than ECON Mode at the same accelerator pedal position. In NORMAL Mode, the engine will kick in before you reach the click in the accelerator pedal. The Clarity will stay in NORMAL Mode when you restart the car.
Press the SPORT button to select SPORT Mode. SPORT Mode not only remaps the accelerator pedal to be its most responsive, it also retains the Deceleration Paddle selections until you change them. The engine will start even earlier in the accelerator pedal's travel than in NORMAL Mode. The Clarity will switch to NORMAL Mode when you restart the car or when you press the SPORT button a second time.
Warning: SPORT Mode is addictive and leads to other bad habits like smoking and drinking. I stay strictly in ECON Mode around town and add HV Mode for expressway travel.
You can accelerate as quickly in ECON Mode and NORMAL Mode as in SPORT Mode, but you have to press the accelerator pedal further in those more moderate modes. When the accelerator pedal is floored, you're getting the full 181 horsepower of the electric traction motor (powered by both the battery and the engine-powered generator) in any of the three modes.
HV Mode is sort of a super mode that works with the three modes just discussed. The Owners Manual doesn't use the word "Mode" with HV, but it's a mode in my opinion. HV Mode is where Honda's computers work their hardest to maximize the car's overall efficiency. In HV Mode, the Clarity's computers can select from EV Drive (battery only), Hybrid Drive (engine + battery), and Engine Drive (engine + battery with the engine connected through a clutch to the single-speed transmission at highway speeds only). A very tiny gear appears between the wheels on the Energy Flow display when Engine Drive is active. Engine Drive must be very efficient or Honda would not have included so much extra hardware implement it.
For some Clarity drivers, HV Mode retains the battery charge at the level it displayed when the HV Mode button was pressed. For others, like me, the battery charge slowly decreases as I drive in HV Mode. It doesn't bother me much, but I wonder why the Clarity doesn't steal a little engine power as needed to maintain the charge when it dips.
When you fully deplete the battery of its charge (two bars will still appear in the battery charge gauge), the Clarity switches to HV Mode but does not display the HV icon on the dash. I guess Honda doesn't display the HV icon in this situation because they don't want you to think you can turn off HV Mode by pressing the HV button.
HV CHARGE Mode is the least-efficient mode you can select, it's primarily for building up a charge for the next mountain climb after you used up all your charge earlier. The Clarity is much more pleasant to drive up an incline when you have some battery charge available to help out the anemic 103-hp engine.
If you haven't ordered and received your free Owners Manual from Honda, you can download the
PDF version and read much, much more information than is available in the Owners Guide that comes with the car. The PDF version is worth having just because it's easier to search than the printed Owners Manual.