Love thy parking lot

This is Wentworth parked today, right next to the exit of the parking lot.



Here is everyone else, close to the building, but nowhere near the exit.



I know, I know. This looks like some extreme nutbag case of getting your money's worth for every last drop of gas in the tank. In a small parking lot, well, yeah, that's true :-D. In a large lot like this, if you're interested in upping your mileage, the lesson is to always park facing out right near the exit. Always. No exceptions. Unless everyone starts doing this, in which case I'll have to retract my position so I can get the good parking spaces :-)

You're basically getting around 0 mpg as you wallow around in traffic right near the startup. Remember, miles per gallon can't simply be averaged together. If you get 5 mpg for the first minute as you idle, check your phone, turn on the radio, then slowly progress out, and then get 25 mpg for the next minute when you're driving at speed, you can't say you've gotten 15 mpg ([5 mpg+25 mpg]/2). Those low miles per gallon act very heavily as a weighted average. If math bores you, skip the next paragraph and just read the point below (secondarily, go buy a math book).

If you patter around at 12 mph for a minute, at, let's say, 5 mpg for 0.2 miles, you've used 0.04 gallons of gas. Let's say you manage to go another minute at 35 mph, getting 25 mpg in any number of large, shiny sedans with more horsepower than you can shake your fist at, thus covering 0.583 miles, using 0.023 gallons of gas. Altogether you've covered 0.783 miles on .063 gallons, for a whopping 12 mpg.

The lazy person rundown for scenario outlined above:

One minute at slow speeds getting out of a parking lot = 5 mpg.
One minute driving at 35 mph = 25 mpg.
Total "average" mpg = 12 mpg.

Or(!) park near the exit, get right up to that 25 mpg cruising speed. Sure, you used a little on startup, so let's knock you down to 20 mpg. You can see, though, that you'd be off on your trip already with 66% better mileage (20 mpg versus 12 mpg) when compared to the standard close parker. Gas prices are, incidentally, interested in these sorts of percentages, and will reward you for thinking about them ahead of time.

And that's why you always park at the exit of a parking lot.

P.S. Love this sort of stair stepper action! Bar on far left was accelerating up to highway speeds, yet still above 50 mpg over those five minutes. Next from left is highway, as is the next 75 mpg bar. After that lower speeds for better hypermiling in traffic. Tank is looking good, 66.7 mpg display over 396 miles. Should be low 60s in reality.

Fill-up, Tuesday, May 3, 2011

478.0 miles
7.687 gallons
$4.029/gallon

62.18 mpg
3.78 L/100km

Wentworth's complete fueling history

A quite disappointing tank by a couple mpg, was thinking it would easily be 63 or 64 (MFD read 66.2 MPG for 478 miles). Had to re-calibrate the Scangauge down a bit more, probably the bladder playing tricks again.

Somedays you just want to move somewhere where it's flat. Yes, Rhode Island has a surprising number of hills in certain spots. In most spots it's relatively flat, but how do you think we get anywhere? We take bridges over water. Steep, steep, bridges.

I'd like to illustrate a little terrain lesson. There are hundreds (thousands?) of people who ask at PriusChat: why do I only get 45 mpg?

Well...

Besides the 10,000 variables (that's an approximate figure) that could play into it, terrain is enormous. Three days a week I get 25 mpg over the first 2 miles of my commute going up a big hill while the car's not yet warmed up. To do that, I use:

0.08 gallons of gas

I then can usually get over 100 mpg for the next 6.4 miles (I know these figures cause it's the distance to my Toyota dealer!). Once I calculated 136 miles per gallon on this segment when I got all green lights! It's wonderful for gliding after you get up that first hill. 6.4 miles divided by 136 mpg =

0.044 gallons of gas

Together, that's 8.4 miles on 0.124 gallons of gas, or 68 mpg or so.

Let's pretend I could get 50 mpg on the first two miles, say if that large hill weren't there and I could hypermile somehow. That would be 0.04 gallons of gas, plus the above second segment of 0.044 gallons of gas, for a total of 8.4 miles travelled on 0.084 gallons. The numbers are purely coincidental, but you can see that's precisely 100 mpg. If I had flat terrain the first two miles, I would get 100 mpg to my dealer.

But I don't get 100 mpg. I'm a 60 mpg driver, and that's still a good thing. And maybe you're a 50 mpg driver, or a 40 mpg driver, which is also great (average economy of new vehicles sold in 2010 was 22.2 mpg). Sometimes terrain just decides our mileage for us, and we can't do a damn thing about it - except complain on a blog :-)

Some positive notes:

This tank did see my first prolonged highway run over 60 mpg, and I had a whole bunch of nice trips above 70 mpg.

It looks like I'll likely stay in the low 60 mpgs for some time given my current commutes. Next year will be interesting, I'll be living elsewhere and will have a different commute altogether. Time will tell if the new terrain will be kind or not...

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!

Everytime you take a short trip, a kitten dies. And you lose a lot of money.

So you love cruising around town. It's quality fun, no doubt, especially in the warmer weather, driving around, radio blasting Billy Joel (or Creed, or Lady Gaga, or Stravinsky - whatever floats your boat). Nothing like jumping around from store to store during the week, going to the gas station to get gas, heading to the grocery store several times a week to pick up a meal for the evening, or driving down the street to drop something off to a friend cause it's quick and easy.

The zooming around town for every little errand is part of the American culture that stemmed from years and years of gas costing less than water (sort of like wine to the French). The thing is, the prices are creeping up once again, slowly but surely, and these habits from the days of sub-dollar gas prices are costing us.

The general rule is this:

Do not take short trips in your car(!).

Cars get their worst possible mileage in the first five to ten minutes of driving. In the winter, this time is prolonged and the mileage becomes atrocious during the warmup phase. To stop for errands, wait until your car is fully warmed up, and then stop for whatever you need on the way home instead of just after leaving the house. Go for broke on those grocery trips, get what you need for a week. Driving your car three miles on a cold engine, especially in winter, will absolutely kill your mileage. Even in my Prius, I know from my house to the grocery store from a cold start gets me about 20 mpg. If you think you're safe with a 25 mpg average EPA rating car, you're probably getting 10-15 mpg during the first few minutes of cold weather (sitting at the stop light is 0 mpg, by the way!).

Let's do some actual calculations. Let's say you can get 30 mpg in your vehicle (very generous, the US average is below this). You expect to go 240 miles between fillups for a grand total of 8 gallons. My most recent gas price of $3.18/gallon would give us $25.44 for a fillup. Let's assume 1,200 miles a month for a total of five fillups in a given month, for a total of $127.20.

Now let's say that you drive a mere 30 out of those 240 miles on short-distance trips - to the grocery store, etc. At 15 mpg your mileage will instantly drop to 26.66 mpg for the entire tank of gas. You've lost over 11.1% of your mileage, and you're paying 12.5% more at the pump. That monthly gas bill jumps to $143.10.

Let's double that amount to 60 miles of short driving per 240 mile fillup. It sounds like a lot, but if you kept track for a week you would find a whole host of surprise short trips that add up. Bank, grocery store, post office, little shopping trip, gas station, dropping off something at someone's place (cause moving a couple thousand pounds of steel is reasonable to transport a piece of paper...go for your e-mail!) - it's easy to do.

With 60 of your 240 miles at 15 mpg, you now drop to 24 mpg, a drop of 20% from your original figure of 30 mpg, and you pay an whopping 25% more! For what other good or service would you pay 25% more than what you need to besides gas? The premium is enormous. You now pay $159 a month instead of the original $127. It's the equivalent of filling up your tank an entire extra time per month!

For the extra you spent, of course, that adds up into $381.60 over the course of the year. Seems better to save it than to spend it for no reason...

So what's the solution? Besides stopping only after the car is warmed up for errands and doing a lot of grocery shopping instead of a little, don't forget that bikes and your own feet get infinite miles per gallon. Walk up the street to the drugstore. Ride your bike to the post office. It's fun, more relaxing than driving, good for you, and costs you and the environment nothing.