Wednesday, March 30, 2011

Fill-up, Wednesday, March 30, 2011

I discovered that my last fill-up was a partial fill-up due to the second generation Prius bladder system, so I've averaged the last two tanks together. It's a little sad, since you always want to see what your actual mileage was, but the average is what counts in the end. This tank had some amazing mileage, too (pictures forthcoming), which means the last one was a lot crappier than I thought! Mild disappointment.

Last week's:

391.6 miles
6.115 gallons

and today's:

451.4 miles
7.882 gallons

is 843.0 miles with 13.997 gallons.

60.23 mpg
3.91 L/100km

Wentworth's complete fueling history

I drove a lot more than I normally do this week, which I didn't like. Now I know what most people feel like fueling up every five days (it's terrible!). Luckily most of that was for a good cause, since one day I probably drove 50 miles testing acceleration, and another day drove toward Boston to meet Hobbit for a hands-on highway mileage class, probably adding 150 miles or so to my odometer. More on the Hobbit meeting soon, by the way...

The worst part is using all that fuel. I might seek out public transportation when it fits my schedule for the unscheduled night out, though it's difficult given the erratic RIPTA schedule and sparse pickup locations. I should also see if when I'm heading out I could give a ride to a rideseeker. I think I would need just one passenger to beat a Rhode Island bus' mpg per passenger!

Monday, March 28, 2011

Scangauge/Multi-function display discrepancy

First part of the trip that told me something nice was coming. Thank you Scangauge for telling me the exact moment I could start pulsing and gliding.

The end result - not quite the MFD record of 73.3 mpg, but I had a couple aborted pulses and tough red lights. I also tried shorter pulses and some lightly EV-assisted glides which largely seemed to help while heading uphill, especially as I compare the bars around the low mileage bar with the ones in the trip record pic.

Now, which to believe? The 2-3% discrepancy between Scangauge and the Prius is not huge, but just enough to be a little annoying. I'm hoping the Scangauge calibration process that takes a couple fill-ups will help with this. In any case I'll take that mileage any day! Of course, the trip you see is the way home - the way there is just barely over 60 mpg, with more uphills, so the average for the roundtrip is 66 mpg, making me wonder if with my commute if it's possible to ever reach 70 mpg on a tank...

EDIT, 3/30/2011: Continues to be off a bit, but happened to get an identical 67.8 mpg from both Scangauge and MFD this morning on a short 7 mile trip. Filling up soon to hopefully calibrate better.

Saturday, March 26, 2011

Acceleration to highway speeds

I was out trying some hypermiling early this morning around town, attempting different methods, and after a couple loops of a disappointing 80 mpg (if you can get 70 mpg on occasion in regular driving, 80 mpg is outright depressing when you're the only car on the road!), I discovered I had a little scrap of paper and a pen in my bag, and decided to head out for some acceleration tests.

I'd been very curious in particular about how to accelerate onto the highway. Anyone attempting good mileage will tell you what a buzzkill it is to accelerate to 60 mph and watch the hard earned mileage bleed off your screen.

So I set out for a limited number of highly unscientific tests, but whose results were clear enough to produce some useful (and for me, surprising) results.

I chose to start accelerating from 10 mph since that would simulate moving slowly as you might at the start of an onramp, but also give you an idea of accelerating from relatively close to zero. I did it from two locations to give myself some data from the roundtrip. You can tell from the numbers below that the first direction is net downhill, and the second net uphill. Both accelerations were on slight uphills leading to the highway. It might be of interest to know that the first one, with net downhill, had a tougher initial acceleration than the other direction, but still came out way ahead.

I decided to measure my acceleration by the percentage of gas pedal depression, programmed into my Scangauge as an XGauge. The margin of error is about 0.5% for this, since it's really very difficult to keep a perfectly steady depression percentage, even when staring at the data right in front of you. As a subjective measure to help everybody else in the world who doesn't have a way of precisely measuring this percentage, I'll break it down like this:

  • 35% depression = stuck behind a granny/school bus driving, or the stereotypical annoying Prius driver holding up traffic
  • 39% depression = normal acceleration for 90% of people out there
  • 45% depression = the asshole who's gunning it past everyone, instant mpg readings in the teens

I reset the Prius' consumption screen just before accelerating, and used that to measure mpgs, since it would be impossible to reset trip data while moving on the Scangauge and then switch to the "Gauge" option quickly enough to make sure the percentage of gas pedal depression was correct. After accelerating I'd switch to cruise control as soon as I reached 50 mph. Other details listed in "notes" in chart below. I picked some signs to go by as my final points, and this is what I got:

I'd like to first address one thing: notice in the downhill run, 45% gas pedal depression, run 1, I got bizarrely better mileage than any of the runs. I have a feeling that the car was in warp stealth at one point in the trip that significantly raised its mileage. I don't know why it did it that time and not on the others. In any case...

Secondly, as a point of interest, there were numerous times in parts of the downhill run where cruise control triggered a no arrows state! Unfortunately the excitement proved too much, and I forgot to check battery current, but RPMs were low at this point (900 something if I remember right), and was not just a warp stealth transition. It would stay like that for 10 seconds.

For the results, even with very few data points, it seems that when a net downhill drive was coming, light acceleration produces the best results. When a net uphill is coming, a very aggressive acceleration is best to get you up to speed. Remember that both onramps were uphill, so I was already up to 50 mph by the time I was even reached the downhill sloping portion of the downhill drive, and yet still light acceleration was better. Of course, as you can see, the difference in end results is so minuscule between your grandma and your local high school idiot, I guess a more practical way to interpret the results would be to not give a damn and just drive the thing!

Fill-up, Friday, March 25, 2011

EDIT: This was a partial fill-up due to a pesky, contracted Prius bladder. See this post for the real details.

391.6 miles
6.115 gallons

64.04 mpg
3.67 L/100km

Wentworth's complete fueling history

A good week and a half of driving. Nothing too special, no crazy drives that knocked this out of the park or brought down the average, just consistent drives right in the 60s.

Prius display read 63.8 mpg. Most people report an overestimate, but so far, compared to the actual fill-up and now my Scangauge readings, it looks like mine seems to be fairly accurate.

I wanted to fill-up since a. there's another gas sale Friday in my town, so on either Tuesday or Friday now I can get discounted gas prices, and b. with the new Scangauge, I wanted to compare the Scangauge's mpg reading to the Prius' mpg reading to my calculated mpg readings to see how close they are. Also, to calibrate the Scangauge to give the most accurate readings, you need a couple tanks in there. Rather than go 500 or 600 miles just to prove I can, I figure I should be nice to the fuel pump and just give Wentworth a little gas (I maybe could have worded that better) whenever convenient.

I did start using some more electric-only driving, but not much. As I discovered in my last post, especially at slower speeds, you can maintain or just about maintain speed with a marginal increase in voltage from the traction battery. For the same or less energy as warp stealth* I can prolong engine-off glides longer without being a huge draw on the battery.

*a low energy highway mode for you non-Prius owners. It can be used over 42 mph in model years 2004-2009 and over 46 mph in 2010-present Prii, maintaining speed on slight downhills at about 900 rpm with complete fuel cut for important fuel economy increases.

Wednesday, March 23, 2011

The Scangauge has arrived!

Awesome mpg in a regular commute (no, I didn't hold up traffic to do this...), 71.8 mpg over 12.1 miles in slow, one-lane traffic over a half hour or so with Scangauge. Usually only get 60-65 mpg on this trip without extra instrumentation. You also see in the background my current mpg for the entire tank on the Prius' display.

The Scangauge, as many Prius regulars know, is a nifty little device you hook up to your OBDII port, the port usually found under the steering column above the gas pedal in many cars that mechanics will use to communicate with a car's computer. For non-Prius regulars, it basically is a little screen that displays various real-time operating conditions in whatever car you decide to use it, including instantaneous miles per gallon, as well as providing you with things like average speed, top speed, and overall mileage for the current trip, day, previous day, and tank.

I was pretty reticent to get it, mostly because of its $160 pricetag, and for someone already getting near 60 mpg, I couldn't imagine how it would help improve my fuel economy enough to pay for itself. It's not even a device that gives you better mileage, it's just a display of various info that you have to put into action.

Luckily I had saved up a boatload of gift certificates, and was getting increasingly curious about the inner workings of the Prius, so I sprang for it, and just got it today.

I headed out for a test run, hooked up the device, and set a couple parameters out of the dozens offered that seemed most useful for my non-highway driving or which piqued my interest for odd reasons:

-Engine revolutions per minute - that's right, a Prius does not have a standard tachometer, ugh (RPM)
-Engine coolant temperature (FWT)
-Traction battery current (BTA - added as XGauge)
-Percentage of gas pedal depression (Gps - added as XGauge)
-Average trip mpg (AVG)

You may wonder why I had average trip mpg on when the Prius can do that itself. Firstly, the Prius typically overestimates by 5% or so. Secondly, to test that very issue out, I haven't been resetting it for each trip on this tank of gas, but rather letting the overall mpg build over several hundred miles to compare the end result with the hand-calculated mileage I'll get when I fill up next week.

Later on in the day I drove to work, and discovered a couple things.

Revolutions per minute

The first change to my driving was rate of acceleration. From a stop I had been accelerating what felt like a nice, fuel-efficient conservative pace, but which was in fact far too slow and laborious. When there was a clear road, I would accelerate to about 15 mph using electric only per a comment of Wayne Gerdes at, then engage the gas engine, but had been accelerating from that point with RPM a couple hundred too low. Today I tried accelerating to speed between 1400-1600 rpm depending on the terrain, and trying to keep it right around 1500 most of the time, and as you saw above, had a wonderful series of five-minute bars with gliding.

Here is an older mileage pic over basically the same route. Compare to above.

Just visually it's obvious that accelerating around 1500 rpm is much more efficient for pulse and glide than what I was doing before. For non-instrumented fellow Prius owners, note that typically this acceleration had the instant mpg showing about 85%-100% of the current mph value. Occasionally I was deadbanding (no arrows to or from battery on energy screen) during these pulses, but when possible I would ease up to get some flow into the battery.

Coolant temperature

The Prius has several stages of operation, explained in this famous posting by Hobbit. To sum up for non-link readers, you can measure which stage the engine is in by monitoring the coolant temperature as it heats up. One of the key temperatures to reach is 163.4°F, or 158°F, depending what you read, and at that moment, assuming a couple other parameters are in place, you have use of full hybrid operation, including the essential option of turning the engine off for a glide, or using electric vehicle (EV) mode if desired.

One of the huge annoyances, especially in the winter, is running into a big downhill in the first few minutes of driving. If the engine hasn't warmed up to 158°F yet, you're going to burn gas while going downhill in your Prius, whether you like it or not. The magic of having the coolant temps right in front of you is being able to approximate how soon you'll arrive at full hybrid mode, and perhaps use the engine a bit more if needed for temp maintenance. You then know the exact second when you can switch to its most efficient state of operation, the glide. Today my warmup phase was a good percentage more efficient than in the past with this knowledge, and I also managed, on my required short trips between clients of about 3 miles, 3 miles, and 4 miles, to get 60 mpg, 50 mpg, and 50 mpg, respectively. How many 3-mile trips do you usually get 60 mpg on?!? Only possible with the perfect timing afforded by the Scangauge.

Traction battery current

There have been plenty of debates on the use of EV, and its potential deleterious effects on mileage. For non-Prius owners, you might be surprised to learn that EV mode is actually rarely desirable, since much of the energy from the battery comes from the gas engine - you're burning gas and converting energy back and forth to charge the battery, so technically it's more efficient to avoid conversion losses and just go for straight pulse or straight glide. The thing is, from observations today...

Sitting in park: 0.9 to 1.0 amps
Use of headlights: +1.2 amps to current current (muwaha)
Neutral glide: 1-2 amps
Foot off the pedal creep from zero mph: 3 amps
Glide in drive: 5-6 amps
Warp stealth with little accelerator demand: 10 amps
Accelerating lightly from a stop = 20-30 amps
Accelerating after first turning on the car (exclusive battery use while engine warms up): 50 amps or more(!!)

So, back to the statements that EV will harm fuel a couple situations where I had to go 20-25 mph and wanted to avoid the inefficient ICE at that point, I could just or almost maintain speed with 7-10 amps. EV with a light touch on the pedal is an almost inconsequential increase in battery use, in fact, even less than warp stealth use. It can be used even somewhat extensively over a small distance with less depletion on the battery than accelerating from 0-15 mph in EV, for example. Even going to 15 amps, knowing that pulsing can provide a similar value back into the battery, doesn't seem so egregious anymore.

I will add a caveat, and this is what others had warned about. Even a slight increase in gas pedal depression will bring you right up to 25+ amps, and this is what should likely be avoided for long periods. Yet another little detail impossible to perceive without the Scangauge or other instrumentation.

For preliminary conclusions as to its effectiveness, I'd say the Scangauge won my respect right off the bat, and I easily got 10% better mileage than the already high mileage I was getting. While it might take me a year or two to recoup the money in improved gas mileage for my high mileage habits, someone driving 12,000 miles a year in a 20 mpg vehicle that jumps to 25 mpg will recoup the money in a couple months, and continue to easily save hundreds of dollars a year after that.

Tuesday, March 15, 2011

Fill-up, Tuesday, March 15, 2011

463.0 miles
7.652 gallons

60.51 mpg
3.89 L/100km

Wentworth's complete fueling history

Around $26 for 463 miles of driving. Found that the local BP station drops their prices dramatically every Tuesday, so looks like that's the new fill-up spot.

I was a little surprised that I got over 60 mpg, since I had my usual short trips for clients, as well as one miserable day of rain and wind netting me around 56 mpg for a trip over which I can usually get around 65 mpg.

I also took a wrong turn on the way home from the airport today, and accidentally spent most of the trip home on the highway. Bad news: 58.7 mpg over 68 miles. Good news (besides getting home a little earlier): recalling that I was around 53 mpg when I took the exit for the slower roads at 46.4 miles into the trip, I've calculated that I got 76 mpg over the last 21.6 miles.

This last bit was awesome to see since it was 36°F, but especially because I used a bit of advice I stumbled upon in one of Wayne Gerdes' comments on a post about hypermiling the Prius. **Prius-specific driving info** Someone had asked him how on earth he got the display to read 99.9 mpg for a trip with numerous stoplights and stop signs (just like mine tonight...). He said he would accelerate to 15 or 17 mph using EV mode, then continue to pulse generally keeping his instant mpg at about 1.2 times current mph until kicking the engine off for a glide. Thus, at 20 mph when the engine has just lit, you want instant mpg to read 24 mpg, and so on. This obviously isn't reasonable in traffic, since EV accelerates obnoxiously slow, but on a night like tonight with empty roads, it was worth a try, and paid off. There were stoplights galore - it really is an engineering marvel, this little bundle of steel and electronics.

Saturday, March 12, 2011

One gallon of gas to Boston Logan

Quick posting from Minnesota...

Drove up to Boston Logan yesterday, half back roads, half highway. Low 40s temps, wet roads, some rain. Was at about 70 mpg before the highway, think I would've been up near 75 or more if there weren't so many stoplights on the route I took (even at 5:30 in the morning!). It got down to around 64-65 after going faster for awhile, then stop and go traffic brought it back up for the end.

67.3 mpg over 67 miles - one gallon to Boston!

Thursday, March 10, 2011

"No-gas" Facebook pledge misses the point

Dear everyone participating in this "no gas" day where you just don't buy gas for one day,

The pledged idea is to stick it to big oil. If that's the case, why hit locally run gas stations with razor-thin margins to begin with? Just use less gas regularly. Walk to the store. Bike to the store. Combine errands. Move closer to work. Look up 5 seconds earlier to notice that red light and coast to conserve momentum. Accelerate gently. Never floor it. Keep your tire pressure up. Go the speed limit on the highway. Buy a smaller or hybrid vehicle. These are the real ways to use less gas.

Can't figure out why gas prices are going up so much? Well, sure, supply concerns. But it's the demand[, stupid]! Your average American passenger vehicle got 22.4 mpg in 2009. You are the demand. We are the demand (even Prius owners!). From the Department of Energy: "About 17% of our imports of crude oil and petroleum products come from the Persian Gulf countries of Bahrain, Iraq, Kuwait, Qatar, Saudi Arabia, and United Arab Emirates." From Saudi Arabia by itself comes a measly 10.4% of our imports. Go out and do what I said above and you'll get 10.4% better mileage easily. Can't do 10%? That's going from 22.4 American mpg average to 24.7 mpg.

As soon as you do that we don't need Saudi Arabia.

The entire Middle Eastern OPEC consortium is 17% as stated above. Can you get 26.2 mpg? You've easily wiped out our dependence on the Middle East.

Oh, and Iraq. You know, this place:

We get something like 3.7% of our imports from them. Can you get 23 mpg instead of 22 mpg? Is using all the fuel you want really worth that? Can't you just ease up on the accelerator?

Instead of being "mad as hell" and being "tired of watching the big oil companies laugh all the way to the bank while we all suffer!" think about what sort of suffering each one of us directly contributes to everytime we try to race some idiot that cut us off. This nonsensical "no gas" day is wildly misguided, however well intentioned. Let us use high gas prices as a moment to look in the mirror, not to deflect the blame that is squarely ours.

Tuesday, March 8, 2011


‎"[Boston] Logan [Airport]'s parking garages have reserved spaces for hybrid/alternative fuel vehicles. Drive a clean air vehicle and get a great parking spot. Same rates apply."

Nice little perk! Now, they likely mean spaces right near the terminals, and while it's a cool offer, I'll be looking for the "bad" spots, aka the ones that require a little walk - right near the driving exits.

Friday, March 4, 2011

Wentworth in the shop

So Wentworth had to go get some preventative maintenance done on Thursday. The main reason was a recent Toyota service bulletin (TSB) regarding the inverter water pump. It would be completely covered by Toyota, as it's a potential overheating issue in the second generation Prius (model years 2004-2009), but nothing serious or immediately at risk.

I had also heard the occasional *clunk* while driving over bumps, particularly at slow speeds, and wanted to get it checked out. Apparently, the service department told me, it was the motor mount issue for which a service bulletin had been issued in 2008. It's rather subtle, and you can see on this TSB that "warranty application is limited to correction of a problem based on a customer's specific complaint". In other words, no big deal, most people probably don't notice or think anything about it. This would also be covered by warranty.

Well, after just driving the car home, everything felt fine, it drove perfectly as usual, though I had trouble keeping it in stage 4 on the way home (it's only a 7.4 mile trip - for non-Priusers, stage 4 is the desirable engine stage where the car works in full hybrid mode, allowing you to turn off the engine for gas-free gliding). Nonetheless got 64-65 mpg on the way home. Funny, because I remember my very first drive home from the dealer I got 54 mpg and thought that was amazing. A little adjustment of habits gets me 20% better fuel economy...

Today's drive home. The 64-65 mpg is calculated as a segment of the longer trip seen on the screen - but the key in this image is the wonderful 5-minute bars!

Now, the dealer's service department general response and interaction was another story. I brought it in first thing Thursday morning, if it were just the water pump, there was the possibility it would be all done that day (I didn't know yet that the clunk was a simple fix), so I waited for the call. Nothing came by the end of business hours, so I called to see what was up. Yes, they said, my car was ready, I could come get it if I needed it, they just forgot to call before to let me know. Since they had a part coming in for the motor mount fix the next day, I just had them keep it overnight rather than drive back and forth and then bring it back the next day anyway. At this point, nothing too unusual is going off in my head. No big deal.

The next day, Friday, I had been told they would have it ready by 11am, so I decided not to work that morning, losing the money I would've otherwise made. The allotted time came, as did noon, 1pm, 2pm, etc., and by the time they called at 3pm, I had started my afternoon lessons, and wouldn't be able to go get it even if they sent someone to pick me up. I had previously told them I wasn't free at all that afternoon, which is why they had said it would be done in the morning in the first place. Again, whatever, fine, it wasn't a huge hassle at this point, though certainly annoying, I would get it Saturday morning before heading out to work. They promised to send someone to arrive at 9am Saturday morning and to call when the car left to get me.

Saturday morning comes, I get up early, prepare everything I need for work that morning to take with me to the dealer, and then - well, you guessed it, no one showed up at 9am, and certainly no one called me. When I called them to ask where they were, they then told me the driver was a little late, and would be there in a half hour (in which case I'd be late for work).

So Saturday afternoon comes (that's now!), I just got home, and called them. Quite apologetically they said they would send someone right away to get me. Once you're talking with them, they're all very friendly, helpful, direct, etc., but the whole incommunicado thing rubbed me the wrong way.

So to Premier Toyota of Newport, it's OK to be a little late with something, it happens and it's reasonable, just make sure you give the customer a call to keep them updated! Not everyone is lucky enough to be able to borrow someone else's car, so for those people I imagine those three days would've been a huge ordeal. I was almost thinking of going somewhere else next time, but...

On an extremely positive note, they only did the work I asked for, and preliminarily, it seems they did it well. This seems like a given, but online Prius forums are replete with stories recounting dealers strongly suggesting to replace, say, *both water pumps* when the other one is perfectly fine, charging far too high diagnostic fees for simple things which were obvious and frequent occurences on the car, or even going ahead and "generously" replacing things like cabin air filters (which anyone can learn how to do in a couple minutes online yourself), and charging copious labor fees for the non-authorized convenience.

At Toyota of Newport I didn't have to pay anything, as everything was covered under warranty, and they didn't charge any odd diagnostic fees or suggest I get other costly repairs. The quality of service I think redeems the otherwise rather negative experience, and so I would return to them, asking from the start that they be very direct at keeping in touch.

Wednesday, March 2, 2011

The Lazy (Wo)Man's Instant Higher Mileage Solution

So you might've had a heart attack over the weekend when you were driving by the gas station and realized that prices popped up by $0.15 to $0.20 or so. Sure, $3.30 in Little Rhody, but you can make yourself feel better by remembering that Europeans are paying around $8 a gallon...

Luckily, as gas prices increased 5% from one day to the next, you can decrease your gas consumption by a similar number without much work.

Your tires. They're filled with air, and they need to be. Underinflated tires give you worse handling, significantly more wear and tear on the tires causing early and pricey replacement, and of course steal easily obtainable mpgs from you. If you haven't checked them recently, you're likely below the recommended tire pressure since a. admit it, you may not have felt like checking ("I don't even know how!"), and b. it's winter, so your psi will naturally decrease with the colder temperatures.

To find the pressure in psi (pounds per square inch) to which your tires should be inflated, check the chart likely stuck on the inside of your driver's side door. If not there, check the owner's manual.

Rather than give a step by step, here's a convenient write up at If you don't have a tire gauge, you can buy one for $5 at your local hardware store (oh, go support the little guy!). Gas stations are starting to charge for air, so try to find one that doesn't.

Also, it is possible to inflate your tires slightly beyond the recommended pressure. Firstly, realize this is at your own risk. Secondly, the previous statement is largely because I imagine I have to say that. Thirdly, realize that is a safe practice that can improve handling and increase mpgs by a small but noteworthy percentage. You will feel an ever-so-slightly harsher ride, but I can assure you it's nothing anyone would even notice unless you pointed it out.

On my Prius, the factory recommendation is 35 psi front and 33 rear (there's more weight in the front of the Prius), and I have mine at 41 front and 39 rear. This is standard for many Prius drivers, and is not a personal experiment by any means. The max sidewall listed is 44 psi on this particular tire. It is important to never exceed this number (even though they are designed and produced to withstand it), since any gains beyond a slight extra inflation provide little boost to your mileage, and there is the extreme danger (not just inconvenience, mind you, but real danger) that could arise if your tire ever blew out.

Fill-up, Tuesday, March 1, 2011

392.9 miles
7.126 gallons

55.14 mpg
4.27 L/100km

Wentworth's complete fueling history

With the recent Middle Eastern-instigated spike in oil, you might notice that I fill up more on Tuesdays, when I happen to be across the border in Massachusetts, aka Magical Land of Lower Gas Prices. I realize many folks don't have extra money to spend on gas, but in an imaginary world where people wouldn't have to choose between gas or food, I'd be happy with gas prices continuing to rise, it would be nice for all of us as a hint to use less energy. But I digress...

A relatively disappointing tank, but largely due to circumstances beyond my control. In fact, it's not the tank, really, since that was good for the conditions, but more the individual trips, and the feeling of constantly seeing lower mileage on every single one of them compared to the recent past. I had several highway trips that I never usually take that brought down the mileage quite a bit, seeing mileage as low as 50.1 mpg on the display for some of the shorter trips (yeah, I know, that sounds...whatever, it's low for me!). I also had some torrential downpours and winds (gusts of 40 mph), and a trip of freshly fallen untreated snow and slush, that I managed to get through with 58.7 mpg over 38 miles.

A little trip to New York revealed a wonderful fleet of NYPD Prii.

Now if only we could get around the warm-up in the first five minutes...