After reading: and another article that panned the whole PHEV concept, (along with a few BEV fan-boys panning the HEV concept as well), I am wondering about my plan to use EV mode around town, and HV mode on the highway. Toyota has tuned the Auto HV/EV mode for minimum energy consumption, but they don't know my cost of recharging, nor my cost of refueling so they cannot drive for minimum cost to the car's owner. I'm going to have to determine what my gas MPG is in Auto HV/EV mode, which is much more complicated than MPG in HV mode.
First, the article being quoted was about Toyota hybrids, not the PHEVs. The EV mode being discussed isn't one that is powered by a charge from an outlet. It is a low speed mode Toyota installed back on the gen1 to move the car out of the garage to get the lawnmower out without the engine firing up, and to not disturb the neighbors with engine noise when leaving and returning home. For most people, it is just gimmick. It is possible to use the EV mode to improve the hybrid's fuel economy. More likely, it will result in use of EV mode making it worse. What mostly happens is the driver gets the timing of using it wrong, or simply over uses it. The car them ends up burning extra gas getting the battery charge back up to where the system is happy. The inclusion of the useless EV ratio display on a hybrid doesn't help. Repeat, this has nothing to do with the Prime. As for the Prime, EV Auto doesn't know how long it will be before you charge the car again. It is just going to use up the grid charge for best efficiency and system health regardless of whether that charge gets used up or not on the trip. If you know your errands will take you beyond what EV mode can cover, go ahead and use HV on the highway. Save the battery charge for when it will net the most miles.
What confuses me most about the decision is Toyota choosing 84 mph to force switch from EV to HV mode. Is that the point gas becomes more energy efficient?
I'm no hyper-miler, but I am the hyper-curious type cursed with a not-very-quiet question stream inside my head which I can rarely ignore. I am not interested in my ECO Score, nor am I willing to piss off the idiots behind me to maximize my miles/kWh. I do like to have an approximate model for complex systems, and test the quality of my model. I do just get in my Prius Prime and drive. The over thinking comes later, when I get home. I thought retiring would help me relax - it turns out work was a useful distraction.
It was chosen by engineering limits and marketing. The max motor outputs with the drive train gearing sets the limit for the max speed possible. The marketing comes in with buyers wanting a 'full' EV experience. That is minimal time the engine is on. If the goal was to maximize overall efficiency of electricity and gasoline, the engine would come on sooner.
Yeah sounds great if you could charge everyday and not start with a cold engine if you run out of charge but yeah hilarious
I found that the Auto HV/EV is great for sporty driving. The acceleration is impressive when the gas engine kicks in. The only trick is that it runs mostly in EV and immediately uses up the traction battery charge during longer trips; so I need to manually select the right mode, if I want to have the traction battery available for certain parts of the drive.
Yeah, Auto mode was gimped in North America. In Europe and Japan it's assisted by a function that automatically switches between HV and Auto behaviour to save EV for the most appropriate parts of a longer trip you've entered into the navigation. Works reasonably well - well enough to avoid worrying about manual switching most of the time. Needs to learn the route though, doesn't seem very effective in a new route. HV is favoured on high speed sections, uphill, or acceleration spots like speed limit increases.
