Prius at 10,000

Our 2005 Prius has just passed 10,000 miles, and we’re generally very happy with it. We made it to 5000 in only 3 months, but 10,000 took another 5 months thanks to our use of the vanpool to work.

Gas mileage is the most prominent feature of the Prius, so I’ll start with that. I didn’t expect the 60/51 EPA estimates and have been pleased to average around 45 MPG. Since the Prius gives you per-trip historical mileage information, you can see some trends in mileage, and the main trend is that the mileage sucks when the engine isn’t warm. That’s likely true of all cars but may be more pronounced on the Prius since it has to warm up the engine so it can be turned on as off on short notice. As a result the first five minutes or so of any trip generally produces only 25 MPG or so. And if you’re making a lot of of short trips, it brings down the average. Highway mileage is pretty consistently been around 50 MPG.

Prius Mileage 97.6 MPGHowever, on my last trip to Florence, SC, I got the 97.6 MPG on flat surface streets for the first 7 miles after filling up. I have to be suspicious that the fill-up may have interfered with the mileage computation. But maybe the route was particularly suited to the engine battery usage—it must have been similar to the EPA test course, at least. For the next 200 miles, I got 56 MPG, mostly on the interstate.

Engine performance and handling have been fine. I thought I would have to give up some acceleration with such a small engine, but I haven’t noticed any problems. Seems as zippy as our 150 HP Passat. My only complaint is that the traction control is not as good as on my 1995 Saturn, but it’s only kicked in a couple of times, and maybe I’m just not used to it. The engine’s ability to switch between power sources smoothly is still amazing.

Controls and Gauges
While the engine computer is impressive, the user-side of the computer and the interface in general is a bit of a let down. The LCD screen is excessive without the GPS option and the trip computer has fewer features than the one on our 2000 Passat. And it doesn’t have a “miles remaining before empty” indicator that many cars have these days.

Prius Steering Wheel ControlsThe controls aren’t that great either. Take a look at some of the steering wheel controls. The notion of up and down are represented in three different ways. Vertically with dimpled “+” and “−”, horizontally with flat “â‹€” and “⋁”, and diagonally with dimpled “â‹€” and “⋁”.

The mostly annoying gauge is the digital fuel gauge. I don’t think I would mind it being digital if it were linear. As it is, the first bar lasts about 100 miles, and each subsequent bar lasts 20-30 miles. I don’t know how long the last bar lasts, but when I fill up I can only add 8-9 gallons to the 12 gallon tank. So either the tank isn’t getting full or there’s plenty of gas left when the gauge gets down to one bar.

Air Conditioning
The temperature control can be manual or automatic. The manual is inconvenient to use since the controls are virtual buttons on the LCD panel instead of knobs you can feel. The automatic works well, but you can only set one temperature for both heating and cooling. You can’t set a range or tell it only heating or only cooling. So if I leave it set at 70° in the winter and the car gets warm from sitting in the sun, when I turn it on, it will start cooling the car to get it back down to 70° even though it’s 50° outside.

Controls aside, the air conditioning works really well. It heats up and cools down quickly without any noticeable affect on the mileage. (I’ve read that the air conditioner is more efficient than most since it runs directly off of the battery.) As a nice touch, when it needs to heat up a cold car, it doesn’t start the fan until it can actually blow warm air.

Interior Room
I’ve always liked the utility aspect of the hatchback form factor, and the Prius lives up to that expectation. We’ve been able to carry some pretty big items with the back seat down. For seating, the interior is pretty roomy. The backseat has lots of legroom, but it’s lacking on headroom because of the sloping roofline. I don’t think passengers over 5’8” or so would be happy for long in the back seat.

Bottom Line
Still fun to drive and performing well.

Math Challenges Done

Maths Challenges Progress GraphI finished the last of the math programming problems. Actually, it’s a temporary milestone since new problems are added every few weeks. At right is a graph of problems started per day with a LOESS smoother applied. The data are from the creation date of the program files, and the few problems that I solved without coding are not represented.

A lot of the problems involved combinatorical counting, so it helped that I had just been reading the excellent lecture notes from MIT’s Mathematics for Computer Science course.

Innoculous Misspelling

As I was documenting something as innoculous today, I thought I better double-check my spelling. Google works well as a spell-checker, either giving you a definition link or suggesting the correct spelling if it’s not a word. For once, Google was at a loss for words. It offered neither definition nor correction but just links to 590 pages using the word. 590 links is a pretty good sign a word is misspelled, and badly misspelled at that; by comparison, incredable gets over 150,000 hits (and a suggestion with the correct spelling).

Next I tried the dictionary widget that comes with OS X 10.4. No luck there after trying several possible alternatives. Unlike a real dictionary, I was unable to browse for words that started with, say, inno which would help me out in case of any unsuspected silent letters. Noticing the widget also had a thesaurus (32,000 Google hits for thesauras), I looked up synonyms for harmless and immediately found innocuous. Of course!

Later I tried my email app’s spell-checker on innoculous and it did figure out what I meant.

More Election Graphs

Following up on my instant fame as an guest author, here are two more graphs from the Chapel Hill Town Council election results. The first is a mosaic plot, which is close to what Mark Chilton was suggesting, I think. For each cell, the width represents the votes in that precinct, and the height represents the percentage in that precinct that voted for the candidate, so the area shows the number of votes for that candidate in that precinct. Precincts are alphabetical; candidates are in order of overall finish. Unfortunately, I couldn’t sort each column differently, as Mark suggested, so it’s not clear who “won” each precinct. Click graph for larger version.

Chapel Hill Town Council Results by Candidate

The second graph is more statistically relevant (ignoring the fact that the “Absentee” early voting precinct is not really comparable to the other geographical precincts). Each box plot summarizes the percentage outcomes for a given candidate in all the precincts. Assuming a normal (bell-curve) distribution, points outside the “whiskers” of the box plot are likely to be outliers affected by factors other than random variation. (Testing for normality indicates that only the Cutson and Baker results do not follow a normal distribution.)

Chapel Hill Town Council Results by Candidate

I labeled the outliers, though the Northside and Lincoln labels overwrite each other in the Thorpe column. The box plot outliers show Mason Farm as significant for Raymond, though it was not noticeable from the overlay line plot since that precinct had so few votes.

Election Results Graph

Orange Country provides timely online election results, and their HTML is friendly enough that is can be imported into JMP. Below is a graph I came up to show the Chapel Hill town council results by precinct. Precincts, along the horizontal axis, are sorted by number of total votes. [Click graph to see full resolution version.]

Chapel Hill 2005 Election Results by Precinct

I’m thinking there’s a better graph using area, but this overlay is the best I can do easily. At least it shows a few interesting pieces of information:

  • In general, not much variation among precincts.
  • A few significant-looking exceptions to the general case: Cutson in Cedar Falls, Easthom in Patterson, Thorpe in Northside and Lincoln, Baker in Absentee, Harrison in Durham.
  • Absentee was by far the largest “precinct”. [Sorry for chopping off the top of the graph, but otherwise there’s too much unused space in the graph; Easthom and Kleinschmidt got over 500 there.]
  • There is a significant difference in votes per precinct. Is it worth campaigning in Battle Creek and Country Club?

Looking at the voter turn out statistics, it’s clear the main factor in the votes per precinct is just that some precincts have more registered voters than others (I don’t know how registered voters correlates to population, though). However, there are exceptions. The smallest (in registered voters, that is) precinct, Weaver Dairy Sat. (is that Carol Woods?) had the fifth highest voter turn out with over 68% voting. And two of the largest precincts, Battle Creek and Country Club (are those UNC?), brought up the rear, due to a measly 2.4% turn out. So the graph doesn’t tell enough of the story there; those precincts are worth campaigning in if one can increase the voter turn out.