Prius Warm-up Stages and Efficient Driving

Wow. Ok, apparently I have a lot to learn. What is this P&G you speak of? I had not heard of any way to "drive my Prius"...

 

The "search" function will quickly find many threads with more technical details.

I would suggest looking at ScanGauge II or Android+Torque to get live, detailed, driving metrics. Then you'll be able to map engine coolant temperature versus engine operation and adjust driving style to current conditions.

Bob Wilson

 

At start up, allowing the engine to do it's first on off cycle before driving actually improves your overall mpg and emissions output (warms up the catalytic converter). After that it's up to you to find "your" sweet spot by means suggested or that of your choosing.

 

I set the displays to show the Hybrid System Indicator, and pretty much anytime accelerating, try to keep it in this zone:



I don't always succeed, for various reasons, like grade, impatient traffic, etcetera, but I try.

 

I use a different driving strategy:

• Only when engine too cold to go off, below 40C engine coolant temperature - I will take the neighborhood route, 25 mph, and shift into "N" when the car can coast.
• All other times, I drive +95% on cruise control - speeds above 23 mph and above 40-52C engine temperature.
• Highest efficient-power rpm - 3,200 rpm, this is the highest EGR % power point and typically seen climbing steeper grades.
• Above 3,200 rpm - only used as needed for rare, exceptional conditions like . . . sitting at a light with a noisy motorcycle to left, 3-lanes become 2 within 1/4 mile, and in the lane that ends. Shift into "N" to keep engine OFF; floor accelerator; light turns green, and; shift into "D" . . .

Bob Wilson

 

Year round, I'm running 52 MPG with both the 2003 and 2010 Prius. The 2010 Prius does it about 5 mph faster and better in cool weather. For my daily commuter, I'm still using the 2003 primarily because it ain't broke, performs well enough, and is a lot smaller for parking and handling.

Bob Wilson

 

Bob, in post #10: "40C" should read "40F"? (purely editorial)

 

^ Try it.

 

We learned our techniques by experimentation. I have no idea about your route and types of hills. My general rule:

• follow (DO NOT TAILGATE) the slowest traffic - this lets you appear "stuck" as opposed to being the rolling road-block. Following traffic will pass without giving the Prius a second thought.
• cruise control is my favorite technique:
  • pat stalk up - increases speed 1 mph for each pat, up to three stacked
  • pat stalk down - decreases speed 1 mph for pat, up to three stacked
  • just trim the cruise control to follow easy

Bob Wilson

 

I agree with Tideland about S1a; I back out of my driveway, then drive to the stop sign at the end of my road at slightly-higher-than-idle, and then continue at that speed to a stoplight that's maybe 100 feet from the stop sign. By that point, I'm usually out of S1a. The road there has a speed limit of 45, so I'll then just go to DWL - keeping the HSI right at the halfway point is quite efficient, and the car warms up fairly quickly because the engine is always on.

Of course, I don't always take that particular road, and sometimes I start from somewhere that's not home (obviously)... In that case, I try to anticipate when the car might be more willing to shut off the engine (it has a VERY strong desire to turn it off at 40°C and again at 68°C, assuming you end S1a below 40°C). I plan a pulse so that it peaks right when the coolant gets to that temperature, and then glide for as long as I can. When the car is still warming up, I'm a little more willing to use the electric-only side of the HSI if I just need a little extra power to make it to the next place where I need to slow or stop - once the car is warmed up, I'll avoid using any electric power. By using electric power that way, I can avoid having the engine running as I'm slowing or stopping, if it had already stopped while I was moving.

My average has been climbing up to about 54 mpg recently, but I'm definitely held back by traffic (and my wife using the car; she puts probably at least 5 times more miles on than I do these days). Last week, I had a particularly enjoyable 25-mile round trip (with 2.5 hours of cooling in the middle) where I got about 78 mpg - partly through good luck with traffic as rush hour was ending, and then partly through a lack of traffic on the way home late at night.

Anyway, try lots of things, and do what works well for you. There's no one "right" way to maximize your efficiency, I think there are just too many variables.