This picture was taken on August 24, 2004. This is what's happened between then and now: I've done my own oil changes regularly. I have had no major problems. My radio did die but Toyota quickly replaced it for free. My OEM tires are ready for replacement. Priapus has served me well, hauled several hundred pounds of wood and miscellaneous other odds and ends, been featured in news articles in print and online as well as televised. It's not the most informational or impressive four-year report I know but it's all I got right now. If you want more information about four years of ownership, just ask.
Your lifetime and average mpg seems to be increasing. Does that mean you're continuing to improve your pulse and glide technique?
Hi Tony, I want to know how you managed to drive on your original equipment tires during four winters in Chicago, without getting into a serious accident... Seriously, congratulations on your steadily improving mpg record!
Congratulations, Tony!! Thank you for taking so much time to share your experiences and to offer helpful advice. My Prius ownership experience is much the better because of your great contributions through PriusChat.
This morning, when I was thinking that it's been four years, I had a better original post in my head. But as I was typing, something came up that required my attention and I didn't have time. So yeah, my Lifetime Average has increased steadily: 8/2005 : 48.0 8/2006 : 49.5 8/2007 : 52.1 8/2008 : 54.1 As has my 12-month Rolling Average 8/2005 : 48.01 8/2006 : 52.14 8/2007 : 57.70 8/2008 : 60.56 Because I have not been tracking the price of gas, I can not fairly draw an apples-to-apples comparison to the Buick Regal I traded in. But I know that the Regal averaged 22mpg. My sketchy math indicates that at an average 22MPG, the Regal would have consumed 2,239 gallons of gasoline in the last 4 years. Priapus has only consumed 910. So while I can't compare prices, I can say that I've reduced my dependency by 1,328 gallons of gasoline. Godiva: I would have to say that my PnG technique has improved. But I've also changed my route to work to better facilitate hypermiling. And since I drive the same route every day, I can try different things: coasting here, pulsing there. . . But of course, when there's traffic, all that goes out the window. Mainly, I learned to rely on the battery less and less as time has gone on. We all know that the battery helps the mileage, but when used too much it will hinder it. For this reason, I care less these days when the ICE is running. Even if it seems to be for no good reason. Any minor hit I might take will be justified by the higher SoC which will help me up ahead. Granted, there are still those spots where I struggle due to long-distance creeping and steep hills, but that's where I try to keep in mind that the tank average is just that: an average. Don't fret the hills; make it up on the straight-aways. Pat, though it gets snowy, I proffer that there are really only a handful of days when the streets are really snowy. And even then, it's not all that bad if you've grown up with it. Personally, I've found no fault with the Integrities. I'm considering getting another set next month. Most importantly, I've found that a clean Prius is a happy Prius. And isn't that really what matters? :thumb:
dang tony! i'm impressed at those mpg numbers. i also can't believe you're still on the oem tires... we just put on our 3rd set. do you use high psi in your tires?
8/2004 - 8/2006 : 33f/35r 8/2006 - 8/2007 : 42f/40r 8/2007 - Present : 52f/50r My spreadsheet says that I'm running 57f/55r. I did that for a little while but then settled back on 52/50.
The relationship of MPG vs. Ave. Temp. is impressive. Folks should click on the image to view it full size to really appreciate it. You've illustrated a response of about 0.4 MPG/degree F over the range from 20-70 F. I expect that somewhere above 75 F the mileage would begin to decline again.
Somewhere I have a Minitab statistical analysis of the temp/mpg relationship. There was a 95% confidence relationship between temp and mileage. Because of the difference when the tires were overinflated, I had to split the data. But even doing that shown a very direct and specific correlation.
I'm sure that the correlation is stronger than that if you were to factor in/out the improvement in efficiency with time and air pressure. Rarely do you get process correlations that are so strong and so obvious.
Just wondering why you would have this expectation. I don't have any data to back this up (well, I only have my own mileage numbers), but my experience shows that mileage goes up as temp goes up, even into the 80s and 90s. We've had cooler mornings of late, and I've noticed my morning MPGs are a bit lower than they were in July and early August.
There are several reasons to anticipate a mileage drop: 1. Primarily due to AC demands for driver/passenger comfort. (Depends heavily on humidity and comfort level requirements of the occupants.) 2. Traction battery somewhat outside of its comfort zone--if the battery is hot the system is reluctant to charge is my understanding. 3. Rolling resistance should increase as asphalt and tires become "stickier". I was intentionally non-specific ("somewhere above 75") with the temperature at which efficiency would begin to decline. Quite a few folks have noted falling mileage as it gets hot and by 100 the complaints appear general. Yes, it has been cooler in the morning in much of the Midwest (59 was the low locally yesterday), well below the "above 75" region I vaguely motioned toward, and I would expect that to require more ICE operation to get the systems to temp. Tony's graph illustrates the temperature relationship well up to about 70+. There are a lot of variables that would go into determining where the break point was, but a meticulous plot like Tony provided should show one if he ran his same routines at ever higher temps. There are so many variables that I would expect to influence the result: driver's comfort requirements (AC set at 70 vs. 75, 78, etc.), humid or dry, length of route, speed of route, garaged or outdoor, sunny or shaded parking, asphalt or concrete road, etc. The combinations will likely be controlling: occupant comfort requires less AC work for ambient of 90 F and dry than 90 F and humid. Short low speed drives in town traffic during hot humid weather will use a much higher fraction of the car's energy for AC than long stretches of open highway in the same weather (or so I suppose.) I sort of expect a large dead band (say 10-30 F, maybe more) where there will be no statistical difference for a large pool of drivers in different regions. However, that doesn't mean that individuals would not notice substantial differences in their normal routines over a tight temp span. p.s. Does anyone know what temp./range/target/deadband the car is using for the traction battery? I would expect that to factor in prominently in finding the break point--just behind occupant comfort settings. But I'm guessing of course.
