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Entries by Bill Wood (78)

Saturday
Aug012009

Small savings above 35 mpg

Recently I wrote about how increasing mpg above about 35 mpg leads to diminishing returns.  Sam Abuelsamid over at AutoBlogGreen just published an article which shows how quickly the savings per year declines once you get above 35-40 mpg:

Imagine, if you will, taking a sheet of paper and cutting it in half. Now take one of those halves and cut it in half again. Now keep repeating the process. As you keep cutting, the difference in the size of the subsequent pieces gets progressively smaller. This simple example is a demonstration of why continuing to increase the fuel mileage of a vehicle has less and less impact once you get beyond about 35-40 mpg.

That doesn't diminish the fun of driving for maximum mpg though!

Sunday
Jul262009

Sony sound overload

With its 12 speakers and 390 watts, you'd think the Ford Fusion Hybrid's optional Sony audio system would sound fantastic - and initially it really impresses with its powerful bass and ability to pump out the volume. 

I had not heard it before ordering my FFH because I ordered the car sight unseen to get under the wire for the $3400 tax credit on March 31.  A week or so later I was able to test drive a FFH at the dealer.  A big smile crossed my face as I hooked up my BlackBerry Pearl to the USB port and played some electronica with deep bass.

Nine weeks later my FFH was delivered.  The Sony continued to impress, but I didn't really focus on it because there was so much to learn about the new car.  Yet a sneaking disappointment was forming - the Sony just didn't sound clean and crystal clear like my old Audi Bose system.  It was tiring to listen to at anything over about 1/2 volume.

I tried fiddling with the settings.  I had hoped it would have a graphic equalizer but it only has bass and treble.  It also has left to right balance, front to rear fade, and "stereo" or "surround" modes.  The "surround" mode is selected automatically when playing a DVD with Dolby 5.1 surround sound - the Sony has 6 discrete channels of amplification for surround sound.  When playing stereo ( from the radio, via stereo bluetooth, from a CD or the Jukebox, or from the USB port), the surround mode simulates surround sound from the stereo signal using Dolby Pro Logic II. 

I couldn't decide between "stereo" and "surround" modes.  In "stereo" mode, the Sony sounds full and punchy with lots of bass and a solid, centered stereo image; yet it often sounds distorted and overblown in the bass, and overly bright in the highs.  In surround mode using Dolby Pro Logic II, it was easier to listen to but often sounded thin and diffuse, as if the mid bass had been sucked out; and the sound stage was ill-defined.

I listened to lots of music and decided that surround mode was doing odd things to the music and that stereo mode provided the rock solid sound I was looking for.  But stereo mode sounded too forward in the car, too bassy, and too bright - it made me tired to listen to it.  After lots of fiddling with the controls and comparing the sound to good headphones, I've decided on the following settings which seem more balanced and accurate:

"Stereo" mode - for a solid sound stage

Fader at "-1" - pulls the sound a little further back in the car and envelopes you more

Treble at "-1" - reduces listening fatigue while maintaining extended treble response

Bass at "-2" - reduces the overblown, distorted bass while maintaining good deep bass

Volume at "3/4" or less - too much volume and its tiring to listen to for any length of time

These settings are much easier on the ears and still sound great.  My guess is that Sony felt compelled to exaggerate the lows and highs to make the system sound impressive.  Too bad they couldn't have just gone for great, accurate sound!

Tuesday
Jul212009

FFH in the wild

I was driving to work today (miserable, rainy) and as I glided up to a light I thought I saw that familiar rear end.  Could it be?  Did it have the tell-tale "hybrid" logo?  Yes!  It was a light blue Ford Fusion Hybrid!  I waved at the driver but I doubt he/she saw me.

I watched to see how he would pull away from the light - usually I can make it to work from this light in EV mode, but you need to start slow over a little rise at the light before going downhill.  He took off from the light though and left me to creep over the rise.

First FFH (besides mine) spotted in the wild!  :-)

Friday
Jul172009

Prius Gen II vs Ford Fusion Hybrid drive test

My daughter has a Gen II Prius (2007).  She's home from school so I took the Prius out on my test loop.  This loop is 14 miles long and I've taken the FFH around it a few times, getting 54-55 mpg.  Its got a mixture of driving conditions - some hills and some relative flats, some over 50 mph stretches, but no highway.  I wanted to see what kind of mileage I could get in the Prius.  While I've driven the Prius before, I've never been able to get more than about 40 mpg in it.  After learning some tricks with my FFH I thought I could do better.

First I did a small drive to warm the Prius up.  I always start my test loop with a warmed up engine so the car is ready to use EV mode.  One of the first things I noticed was the Prius does not have much power in EV mode. Starting from a stop usually turns the engine on. The FFH often has enough power in EV mode to pull away from a stop or go up a small hill.

Prius engine and electric motor driving wheels while battery is chargingThe Prius has an energy flow diagram like the FFH.  The Prius one is easier to read.  The flow lines are color-coded green, orange, red, and dark gray, and clearly indicate flow direction - much easier to interpret than the gradually widening flow lines on the FFH diagram (the FFH energy diagram does indicate intensity of flow by varying the thickness of the flow lines which is nice).

I soon began to miss the gauges in the FFH.  The Energy Monitor screen is the only tool the Gen II Prius has for monitoring what's happening in the drive train. In the Prius it was difficult to predict when the switch from EV mode to "engine on" would From L to R: Battery & engine power, Battery charge indicator, Speedometer, Fuel gauge, Instantaneous MPGoccur because there is no gauge for that, nor is there an indicator for when you are in EV mode. The FFH has a rich set of gauges. Depending on which ones you enable, you can see engine RPM, power draw from the battery and the engine, battery state of charge, instantaneous MPG, when the car is in EV mode, and how much acceleration you can apply in EV mode before the engine turns on.

During my drive I used the "pulse and glide" technique as often as possible.  In the Prius, its easy to move from the "pulse" to the "glide" - there is a sweet spot between taking your foot too far off the throttle and starting to regen and having too much throttle and initiating electric motor assist.  You can easily see when you are gliding using the Energy Monitor because all the flow lines are dark gray.  Getting a good glide going in the FFH is harder - its not as easy to get the exact balance between regen and motor assist. 

The Prius really sings during a glide!  It has less drag than the FFH.  The FFH drag while gliding was explained by Wayne Gerdes as "back EMF build" which I guess means that the electric motors are providing resistance so the FFH is not rolling along completely freely.

The FFH can go faster in EV mode before the engine turns on, 47 mph to the Prius's 42, which means you can pulse up to a higher speed before initiating a glide in EV mode.

The Prius is a great car. I could tell fairly quickly that I would get better mileage, and I did - 70.7 mpg!  I prefer the driving experience of the FFH, but if you're going for MPG the Prius is the one to get.

Wednesday
Jul152009

Glide eMPG

If you're interested in the discussion of pulse and glide in a few of my recent posts, I've posted some ideas on how to determine "glide equivalent MPG" over on PriusChat.com.

Tuesday
Jul142009

Flipping the flip key

The flip key is slightly thicker than the original keyOriginal FFH key on left, flip key on right (click to enlarge)Artiway from Taiwan sells an Audi-style flip key on eBay for the Ford Fusion Hybrid that I ordered on July 2.  It arrived quickly via registered mail last Friday July 10.  Artiway (or "Welly" in his emails) was very prompt and helpful in all my communications with him.

It is a handsome key that is smaller than the original Ford key when closed, doesn't create holes in your pocket, and has a better (to my mind) button layout.  It weighs a bit more than the original key - 46 grams vs 26 grams.  It could easily be made 1/4 inch shorter and still have the same blade length as the original key.

The key came with easy-to-follow instructions for programming it to work with the car.  You must program the key to work as a remote for the doors and the emergency alarm.  You need your original FFH key to do this, which involves rapidly turning the key in the ignition between the second and third ignition positions.  The instructions say third and fourth position, which would be between "accessories on" and the position which starts the car, but that didn't work for me so I used the second and third positions.

You also have to program the "transponder".  The transponder programming mates the key with the car.  Without it, you can use the key to open the doors but it won't start the car.  Programming the transponder was also an easy process, involving both keys that came with the car.  This makes it harder for someone who steals one key to create a duplicate which could be used to steal the car.

On Saturday I set out to get the blade cut.  The owner at our local hardware store suggested a nearby lock company because he didn't want to take a chance on ruining the blade on a $50 key, and he didn't think that the key would fit properly in his machine. 

Ford key has wider ridge around center channel (click to enlarge)

The guy at the lock company had some bad news for me. If you look at the picture on the right, you can see that the ridges around the center channel are wider on the original key than on the flip key.  He said that his key cutting machine uses the ridge to align the keys and that this discrepancy would cause the cuts to be too deep on the flip key.  He was reluctant to risk ruining the blade on a $50 key. 

I emailed Welly and he assured me the key would work (the ridge size difference not with-standing) and that he could send me a new blade if necessary.

Encouraged, I visited another hardware store on Sunday.  Their machine was not able to hold the flip key properly.  I returned to the original hardware store; the owner was not there, and the two people I talked to didn't want anything to do with cutting the key.

Undaunted, I came up with a cunning plan.  On Monday, I returned to the lock company, and had the locksmith select a non-electronic key from their stock with the same blade dimensions as the flip key. He aligned the two keys using the center channel instead of the ridges so the cut would not be too deep.  For $4.50 he cut that key and I tried it in my car - it worked fine in the door and the ignition but with no transponder it would not start the car (it started the alarm instead).  That proved that the flip key would work when cut!  It also made the locksmith less nervous about ruining my $50 key.

The locksmith placed the original and flip keys in the machine and, carefully bending the body of the flip key upwards at the hinge between the blade and the body to avoid hitting the cutting machine with the body, cut one side of the flip key.  When he went to turn it over to cut the other side of the blade, of course he could not bend the body upwards, only downwards.  Uh-oh!  The flip key would not fit into the machine that way!

Now this part really did happen, I am not making it up: I suggested he flip both keys around 180 degrees so that he could still bend the flip key up, and cut with the keys facing in the reverse direction.  He looked at me in surprise and said, without the slightest trace of guile, "genius!".  In twenty years he had not considered doing this.  Shows how ingrained our thinking can get. 

His buddies in the store all crowded around to see this marvel.  After a few more adjustments, he was ready to cut.  "Which direction should I cut?", he asked his boss.  If he cut from the tip towards the key body, as he always did, he would be moving in the opposite direction from what he had done for twenty years.  "Cut in the same direction as you always cut", advised his boss.

I am now the happy owner of an Audi-style flip key for my FFH!

Sunday
Jul122009

The myth of pulse and glide revisited

My post on the myth of pulse and glide generated a number of comments here, over on PriusChat, and at CleanMPG.  I thought I'd respond and clear up a few misconceptions with a followup post here.

A number of people thought I was saying that pulse and glide (P&G) doesn't work.  Nothing could be further from the truth.  I continue to learn about this important technique for getting good gas mileage.  The "myth" I was referring to is the common intuition that if you pulse at, say, 20 mpg and glide the same distance at, say, 100 mpg, then you will average out to 60 mpg total. You actually get 33 mpg in that case and don't get 60 mpg until the glide is 5 times longer than the pulse.  If you assume infinite mpg for the glide, you get 60 mpg when the glide is twice as long as the pulse, which is also not particularly intuitive.

Others noted correctly that the glide is usually longer than the pulse, whereas my example stipulated the pulse and glide as being the same length.  The intuition I spoke about above usually arises when people are thinking of equal length pulses and glides, which is why I used equal length pulses and glides in my example. Here is a chart showing the Total MPG for various glide MPGs where the glide is 1, 2, 3, 4, and 5 times as long as the pulse.

Several people made posts or commented on the blog saying that they had gotten great gas mileage (one poster got just over 170 mpg!) while using P&G. That's great! A couple of things to look at in those results, if you really want to understand the long term sustainability of P&G:

  1. Was the battery state of charge (SOC) at the same level before and after the P&G session. If the battery SOC was lower, the P&G is not sustainable over time with that same great gas mileage as the engine will eventually fire up to charge the battery and shorten your glide.
  2. Was it a round trip? Wind and/or downhill slope can make a glide last longer than it would otherwise. By going both directions, those factors are eliminated.

Some posters were concerned about my use of 100 mpg as an estimate of gas mileage for the glide portion. I picked that number because my first P&G experience was with my old 1998 Audi A6 whose engine does not automatically shut off during the glide. These same posters pointed out that in a hybrid like the Ford Fusion Hybrid or Prius, the glide gets infinite mpg. This is where things started to get hot!  This discussion is not bottomed out yet.  For the mathematical model of P&G that I am using, it makes sense to not think of the glide as having infinite mpg.  During the glide there will be battery discharge - from A/C, or lights, or feathering the throttle to extend the glide a little.  Even without these electrical draws, the electric motors still draw some current. You can account for any battery discharge during the glide by reducing the glide's equivalent MPG. Equivalent MPG is a way to think about the true cost of a given transport mode. When discussing all-electric cars, equivalent mpg is used to determine the true cost of moving the car, even though the car is getting infinite mpg in the sense that its not using any fuel at the time its in motion.  Looking at the big picture though, the car has a cost to operate, when its charged at a later time from the electrical grid. So you'll read about the Tesla having an equivalent MPG of 120 or so.   When you glide in a hybrid car but are using the battery, its the same situation. The battery has to be recharged eventually somehow, and this always involves the car's internal combustion engine (brake regeneration can't restore the whole charge on a round trip due to conversion losses).  To keep the mathematical model simple you can select an equivalent mpg for the glide to account for this battery charge loss, which, if you keep doing the P&G for long enough, will eventually cause the engine to run to recharge the battery.  Here is the simple mathematical model I used for my original blog post:

Distance = Glide Distance + Pulse Distance
Glide Gal = Glide Distance/Glide MPG
Pulse Gal = Pulse Distance/Pulse MPG
Total MPG = Distance/(Glide Gal + Pulse Gal)

If you don't like assigning an equivalent MPG to the glide, then set Glide Gal equal to 0.

Thanks to all the posters and commenters for helping me to refine my understanding of P&G, and helping me to develop the pulse equivalent mpg idea.

Friday
Jul102009

A cheap date

From AutoblogGreen, a report that hybrids and diesels are cheaper to own than gas cars:

Of the 51 hybrid and clean diesel models now on the market, 35 of them deliver a cost-of-ownership that is somewhat or significantly lower than gasoline versions of the same vehicle. The long-time knock against 'green' cars, trucks and SUVs is that their sticker prices do not justify the gas savings. The point we make is that it is not just about fuel. Buyers also need to consider costs such as maintenance and resale value.


Wednesday
Jul082009

The myth of pulse and glide

The math behind "pulse and glide" seems intuitive enough.  At least that's what I thought.  Until I started calculating my total MPG for trips to and from work.  On the way to work I have gotten 60 MPG; on the way back I have gotten close to 40 MPG - that's 50 MPG total, right?  I did the math, and my MPG to and from work is only 48 in that case.

How does this apply to pulse and glide? Pulse and glide is a technique where you accelerate moderately to an upper target speed such as 45 MPH, then lay off the accelerator and glide down to a target speed such as 35 MPH, possibly putting the car in neutral during the glide to minimze fuel use.  Then you repeat.  The idea is that the pulse MPG and glide MPG should average out to some pretty good gas mileage.

Let's say you decide to pulse for 30 seconds, then glide for 30 seconds. If you get 20 MPG during the pulse, and 100 MPG during the glide, it seems natural to assume you'll be getting 60 MPG total - after all, 1/2 of the way between 20 MPG and 100 MPG is 60 MPG. This is the myth of pulse and glide. Please bear with me for a little math of pulse and glide ;-)

Here's a chart showing total MPG for a pulse at 20 MPG and a range of glide MPGs from 20 to 150.  At 100 MPG for the glide, the total MPG for the pulse and glide is only 33 MPG, not 60 as we intuited.  At 150 MPG for the glide, the total MPG for the pulse and glide is still only 35! 

The maximum possible total MPG, even if you use no gas at all during the glide, is only 40 MPG.  Why?  During the pulse you get 20 MPG, using G amount of gas and travelling D distance.  Your mileage for the pulse is D/G MPG.  During the glide you use no gas and travel D distance also.  Your total gas usage is G.  Your total distance is 2*D.  Your total mileage is 2*D/G MPG, or twice the pulse MPG.

So, in our example of a 20 MPG pulse and 100 MPG glide, how far must you travel during the glide to get 60 MPG total?  Five times the pulse distance!

Wednesday
Jul082009

Driving without air

I got a nice little tip from a forum post (will update later if I can remember where) on how to keep the FFH nicely ventilated while driving without air conditioning.  Opening the front windows can be noisy and as on many cars opening a rear window can create a "beat" sound which is annoying.  But if you raise open the back of the moon roof and crack the right rear passenger window about an inch or two, the driver gets a nice cross breeze and its not loud.