Own 2009 pkg 4, has 103,000 miles, want the Prime, but not now if, hysteresis between power consumption and pure coasting (glide, NOT regen.) has been minimized/removed. Story fill in: Currently hypermiling by feathering the foot feed so that the ICE shuts off (not spinning under 41 MPH) and no power draw to E motor, pure coasting. This is fairly easy below 41 MPH, go faster and the engine spins (not on) and the hysteresis drops to just about zero. Extremely difficult to feather foot feed traveling above 42 MPH and not use gas or battery. I like the Prime, but, want to be able to easily coast using no gas and no battery as described above only hopefully also at faster speeds. I'm assuming that it's ability of 100% electric would include a non-energy consumption band in the foot feed range of motion that would allow for pure coasting (no regen.). Does the Prime have the same or broader hysteresis than the 2009? If true, is there a button choice selection like "ECO" that broadens the hysteresis? If it's not there, it should be, since it's much better to not expend energy in the first place than doing regen with all the losses of converting motion -> electrical -> chemical battery chemical. Moderator, if this is the wrong forum please move, and if already discussed, just point me there. Looked off and on and didn't find this specific info. Thanks! I LOVE my Prius and hypermiling ! ! Hysteresis:
My answer is, yes, but in HV mode only. In HV mode coasting is more difficult because it's almost impossible to null the regen feathering the accelerator. It's a little better in EV City, because the regen effect is less evident.
Even if you don't completely null the regen/drive equation, the net result is pretty indistinguishable from having exactly net zero. Plus, I don't know that Gen 2 had any wider hysteresis than newer generations.
welcome! it is more difficult in gen3 than gen2, but that is a result of toyota learning the concept from experience and incorporating it into gen3 software. so you get the same mpg effect without the needless foot wagging and loss of driving concentration. from my experience with prime test drive, it is similar to gen3. you would be crazy not to trade up, you'll never accomplish with your foot what toyota has built into its latest technology. all the best!
Could you just shift into neutral to coast? The Prime has powerful motors. I'm pretty sure the engine is completely off above (and below) 42mph unless it's actually helping power the wheels (or other less common cases like warm-up or B mode). At highway speeds with light pressure on the accelerator it often runs in "small EV" mode (when the overall setting is HV mode, such as after all the normal EV mode ("Big EV") range is used). I don't know how the gen II works. If you coast with your foot off the pedal, the amount of regen is pretty low, and that energy is put into the battery with good efficiency, so the energy lost is tiny. I wouldn't let a tiny energy loss be a factor in a decision to purchase a car. I have occasionally seen around 80mpg on the highway on a 40 mile trip in HV mode with no special driving techniques. But with EV mode I hardly use any gas. I can't remember the last time I bought gas, and the tank is half full.
I thought the ICE shutoff speed had been boosted so much -- to 80-ish MPH on the Prime?? -- that this no-ICE-spin benefit at highway speed overwhelms any EV-mode hysteresis problems. A non-spinning ICE is worth something like a 2 kW drag reduction. Can existing Prime owners verify or correct this speed? It would help me significantly on the extended rolling hills pattern of my usual trips.
