Hi people, This has been bugging me so I figure I would put it out there. Are there any scenarios where it would be more fuel efficient to quickly get up to speed via the power section of the HSI and gliding or is it ALWAYS more fuel efficient to stay within the ECO section of the ICE area? I have been experimenting and it doesn't seem to make a huge amount of difference. Having brief access to the power section of the HSI certainly make me feel less like a grandma behind the wheels. Any experience on this? Thanks
I accelerate briskly with the HSI in the middle of the power section. I almost never floor it. Maybe I'll be satisfied with keeping it in the ECO region in a few years after I turn 60 - naaah.
I typically accelerate to the end of the power section in order not to impede traffic around me. Also I found if I accelerate briskly then I can get up to speed quickly and begin pulse and glide or just glide much quicker and recover any loss of mpg during acceleration.
In the v wagon, at the top of the ECO band the instant MPG is around 23...as soon as it goes into the PWR band it drops below 10 MPG! I saw a good 10% increase in overall MPG just by avoiding pushing into the PWR band when possible (no traffic, flat/downhill lie). ETA: I paid a bit more attention over the weekend, and this seems to be true only above 45MPH for me. At lower speeds, particularly from a stop, it's not nearly as big of a difference.
From a fuel efficiency standpoint, no. Going into the power section is not more efficient. For max efficiency keep RPM at 1,500-1,700 when pulsing before a glide. If you want to test this simply find a deserted section of road and practice pulse & glide while monitoring your efficiency using the fuel economy over time screen. Do 15 minutes one way and 15min another way. If done correctly you should be able to see a difference in the graph. If it looks like this with your technique then you are doing it right.
Thanks for chiming in guys, I still wonder if MPG difference is nominal between quickly accelerating via the power section and gliding vs staying in the eco section and taking twice as long to get up to speed and gliding. I guess like F8L says, the best way is to try it out. I just wondered if anyone has already experimented with this. I have only had my prius for a couple of weeks so I haven't figured out all the graphs and graphics. This is also complicated by the Canadian measurement system of Liters/100k. It in fact is the opposite of your graphs. In our cars the closer you get to Zero, the better off. (which makes the current fuel economy gauge useless since most of the time it is pass the 10L/100K max and I have no clue what the exact number is)
You can fine tune any proposed system by using the segment mileage setting on the ScanGauge. By tracking the increase/decrease in the mileage, you can quickly determine if your system is helpful or not. Check the segment mileage at the start of the cycle you are testing. Check it again at the end of the acceleration phase- it will be lower, of course. Then check it a final time at the end of the glide (or whatever) phase. After several cycles, it will be obvious if both the high-point at the end of the glide and the low-point and the end of the acceleration are increasing. If they aren't, then the system needs to be modified. I have found that excessive acceleration lowers overall mileage for my style of driving and geographic area.
I like to accelerate at the top of ECO zone, just on the line. That's 1700-2000 RPM, depending on speeds. The faster acceleration, less ICE run time. I don't think going partially into power zone is a big deal MPG -wise. Full power/floored gas is a different story. I still like to do it from time to time if conditions require. It' good to exercise the engine.
Your hunch about keeping it brief is spot on. Remember that demand for rapid power results in draw from both the battery & engine, a feature designed specifically for reducing efficiency penalty. This allows you to take advantage by not having to accelerate slowly. There is a taboo about avoiding ever pushing the pedal that hard. My Prius experiences (prior to getting the plug-in model) have been just driving the way you normally would yields great results. With the plug, you actually can't prevent hitting the power-zone in the extreme cold. But then again, you just drive it then too.
