Max MPG Driving Techniques Youtube Video

I live in Northern California, and it's not exactly cold- I would say in the 50s and 60s during the day. I think my driving "skills" are probably the reason.

 

Lisa Jean, I have had my Prius two months and I have definitely noticed my MPG getting better with each subsequent tank as I have improved my driving habits, despite it going down recently because it's now in the teens here. You'll find yourself naturally learning how to watch the gauges so you improve your FE.

 

We average 51 mpg over 4 years in our 2010 in spite of a very short commute and other very short trips. But this time of year we can have tanks at 40 mpg due to cold temps, ice, snow, defrosting, etc. Work on your techniques, but be forgiving until spring when looking at results.

 

If you look at Fuelly - Track and Compare Your MPG and check some fuel economy graphs over time you'll notice seasonal variation. Assuming similar driving techniques throughout the year, the difference must have something to do with seasonal changes. In temperature climates, the seasonal distinction may be minor and difficult to identify from other variables, but cold Winters or cold mornings from high altitude will have a disproportionate affect on fuel economy.
My fuel economy varies from about 5 l/100km (47mpg US) in Winter to about 4 l/100km (58mpg US) in Summer, where Winter days regularly start below 0C.

Track your fuel use and don't be down if you don't get dreamlike numbers in Winter.

 

I want a Tesla T-shirt too!

I was watching the the gauges today and trying to stay in the left half of the bar/using ECO, and I think I'm around 50mpg cumulative now!

 

Be careful, it's addicting!!

 

Thanks for passing on your knowledge; very helpful.

 

great video.

my problem is the commute from vienna VA to DC. 18 miles, and some mild hills, and very aggressive traffic. on my current tank (#2) i'm in normal mode and just trying to be cautious to keep it out of the power zone on the display. Obviously keeping the display out of the red is key, but how much does it hurt the mpgs to "get up to speed" quickly and enter the red zone to get to the speed such that you can pulse and glide... i have a couple hils where i have no option but to go into the red just to get to the speed limit...

 

You might consider getting a small, live-data display, Prius-aware scanner, ScanGauge or Android. Then you can monitor the engine RPM and other parameter to stay in the good zone. But to answer your question:

• until first engine transition to fuel trim mode, ~1 minute - it will suck gas bad
• before 40C engine coolant and heater off - it is going to suck gas even when stopped, the engine won't auto-shut
• after 55-60C engine coolant - it doesn't really matter, just drive

Our 1.8L ZVW30 has 'cooled, exhaust gas, recirculation' that means at higher power settings, it uses some exhaust gas, cooled, mixed with the input air and gas to keep the engine from burning out the catalytic converter. This means the mixture does not not have be 'cooled' by running a rich mixture.

A good rule of thumb is to switch to the energy display and glance at the power flow. If you are not drawing power from the battery for periods of 5 seconds or more, no problem. If you are drawing from the traction battery, see if you can back off a little. Short traction battery power draw is OK but long, sustained, drawing on traction battery power tends not to work all that great IF you can safely use the engine alone.

The reason is traction battery power is not free. What is discharged has to be replaced later. But running on just the engine keeps it in the 'sweet spot' and this is a universal rule for all models of Prius. But SAFETY FIRST! Don't become anal about staying off the battery, just be efficient.

Bob Wilson

 

thanks bob... definitely going to take some practice.

Not a huge fan of more gauges. Heck I'd spend more time watching the gauges....
It would have been nice if the the nav screen could have had an option to display more engine info while driving

 

Join the chorus. <GRINS>

My pet peeve has been the absence of metrics that could have been designed into the instrument display. But I come from an age of analog gauges and remember well seeing:

• coolant temperature gauge
• voltage gauge
• rpm gauge
• manifold pressure operated windshield wipers (Ok, not really a gauge)

There were in the factory delivered cars, trucks, and tractors. What is maddening is these metrics already exist as even over-the-counter, crappy scanners can read them out!

But as a rule of thumb, try to minimize traction battery draw and you'll achieve 90% of what can be accomplished.

You might get a topological map (aka., Google earth and others) and map your commuting route. Try to choose routes where you can do the first mile, 5 minutes, on level ground at neighborhood speeds. This gives the car enough time to reach 40C and efficient operating modes. Route planning pays dividends but don't expect miracles . . . maybe 10%.

Bob Wilson

 

I wish it was that simple bob,

just to get out of my hood. I have to go about 150' up over 1/2 mile to get to surface streets. and once on surface street, I end up going down and back up just to get to a major road. So in the morning I'm screwed.. on the plus side, I'll get the benefit of regen on those hills on my way home. but as I get close to work I have a long, 300 foot drop over 1 mile, great for regen. but its only a mile from work, so when I leave work I have a long hill climb when the engine is still kind of cold.

this is the shortest and quickest route. yes I could go on a toll highway for some of the trip, but them I'm trading toll money , $1.75 each way, spending nearly 4 bucks in tolls daily I don't think will save me the equivalent in fuel on the highway... couple with the fact that I also want to spend the least amount of time in the car commuting...

here is my route on map quest...
MapQuest Maps - Driving Directions - Map

it a catch 22... I could probably get better mileage on the highway. but it will cost me tolls, I could modify my route to try to avoid hills, to save fuel, but it adds time and distance...

 

Let me make a couple of suggestions:

1. When starting car, wait for the "engine surge" that happens about 1 minute after start. This is the transition point to fuel-trim feedback. During this initial phase, the engine is using stored fuel-trim meant really to get the engine started. Your initial hill climb could be in this, inefficient, starting mode. Give it at least a minute.
   1. Better practice, start car with heater off and go back into house for a cuppa. Depending upon temperature, wait for engine to auto-shutdown, it is at 40C. Now the car is in a warmed up state and you can drive a little more aggressively. Have car parked so you can see if the exhaust is coming out the tail pipe.
   2. Poor practice, start car with heater on as the coolant now has to reach 55C before the engine stops. But it makes snow and ice removal easier.
2. Compare MPG and distance over these two, neighborhood routes:
   1. DaysFarm Dr -> Beulah Rd -> Browns Mill Rd
   2. DaysFarm Dr -> Black Eyed Susan Ln -> . . . Browns Mill Rd -> Beulah Rd
   3. Use identical warm-up protocols, reset trip meter in both cases

During very cold weather, I'll use the 25 mph, neighborhood route that takes longer than going to the cross street. But this gives the car time to warm-up to efficient temperatures and often get into the 'hybrid mode' rule set. During warmer weather, I don't need the longer neighborhood segment.

GOOD LUCK!
Bob Wilson

 

bob,

Car is garaged at night so its a bit warmer than ambient outside temp and no snow/ice/frost to deal with.

the route from my place up black eyed susan and around to beulah via browns mill is .7 miles going up the hill on days farm directly to beulah is 1.01 to the same point. and the hill on days farm is higher than the one on blackeyed susan. going on blackeyed , based on topo maps is about a 50' less of a hill, but it over a shorter distance IE steeper hill.

here are two screen captures from mapmyrun showing the hill profile on the different tracks all the way to work. after about mile 4 it all down hill going to work...

 

You're the man 'on the spot' so I'm not about to second guess. Based upon the numbers, with Prius warm-up to 35-40C, I like Blackeyed Susan better BUT you know better than I.

You have a good grasp of the route characteristics and I've tried to share the Prius characteristics. But I will always defer to your metrics.
Bob Wilson

 

you had some great info... and the video was great as well... i've got such a tough situation and still a lot to learn about the car...only halfway through my second tank, in the worst time of year for fuel mileage...

Kinda like back in the day walking to school in three feet of snow, uphill both ways... on each end of the start of my commute I have two largish inclines when the engine is at its worst performance.

question...Since the engine is already at is worst performance on startup...why not take the loss with the car moving?

 

It is a question of burning the minimum fuel for each trip. There is a factor of 4-5 between the fuel burn for power and idle. Furthermore, minimizing the warm-up the engine power until reaching 55-60C, saves total warm-fuel burn(*). Let me suggest the following, measure the fuel burn over every segment of a morning trip.

Using a voice activated recorder, reset a trip meter and start the car. Then voice-record, the miles and MPG to major way-points on the morning and evening commute. Then enter this data into a spreadsheet and calculate the fuel burned for each segment.

My metrics suggest you'll find ~50% of the fuel burn happens in the first 1-2 miles. The rest is burned over the ~75% of the remaining trip miles. Pay attention to where the fuel is burned and you'll see what little, 10-15%, improvement is available. You might also consider a block heater since that can cut out about 1-2 minutes of warm-up.

GOOD LUCK!
Bob Wilson

* - I want to add some technical details.

Engine warm-up is primarily a function of time with a minor effect of load. Combustion gases are at ~2,000C while the engine is substantially cooler closer to 20C. This extreme temperature difference means the warm-up, the heat flow, is limited by the thermal transfer characteristics of the metal. There is about a factor 4-5 times difference between idle fuel flow, 0.30-0.45 gal/hr, and power flow, 1.3-2.0 gal/hr. But a 'cold engine' Prius has poor fuel economy, 25 MPG, versus warmed up, 50-60 MPG. A sustained, substantial load on a 'cold' Prius means burning a lot of gas for very poor mileage. The key to efficient operation is understanding the warm-up profile.

There are a few important temperature points:

• ~1 minute to engine 'surge' signaling fuel trim
• 40C w/o heater - the engine will auto-stop when the vehicle is stopped or in "P"
• 55C w heater - the engine will auto-stop when stopped or in "P". It also stops the engine when there is no load.
• 65-70C - the traditional hybrid threshold but there is evidence it may be lower in our ZVW30.

If you have to climb a hill on a cold-start, it makes sense to keep the car in "P" until at least the initial engine surge. Better still, let the car warm-up to 40C with the heater off until the engine auto-stops (fix a cuppa coffee to sip on, "Honey I'm taking out the trash" e.t.c.) Best, leave the heater on low-fan, in cabin-air recirculate until the car auto-stops at 55C.

Now if you have flat or descending terrain for about 1-2 miles, you have the option of a rolling warm-up. Get the car up to ~25 mph (typical neighborhood speeds) and shift into "N" so the engine will run in "idle" mode. In my case, typically 25-33% duty cycle in "D" and 66-75% in "N". This won't give great MPG, typically 35-40 MPG, but it moves you toward your destination while the engine warm-up continues burning the least amount of fuel.

 

here are pics of the fuel screen. the 630am is the drive to work, andthe 350pm is the trip home

outdoor temps were within 5 degrees AM-PM.. 18*F zero warm-up

I took the same route each way, the only thing that accounts for the .2 mile difference is I have to go slightly past work and do a u turn to get in.

did quick accel to get up to speed so I could glide more. on the way to work. out of the 1o traffic lights I think I only had to stop at 4 of them. Not so lucky on the way home.

 

the video helps even having our prius for a few months now!

 

If I can cruise near the midline where the ICE kicks in, is it better to try to be below it (on EV only), or slightly above it (ICE on a bit)?