Seasons are a-changing

First autumnal evening in the high 50°Fs tonight, and an immediate and obvious shift in the opening mileage of my trip, with the magic 157°F mark reached slowly and deliberately over a lengthier distance than the summery usual. Achieved around 66 mpg on a trip where I would get around 70 mpg. Small, but a sign of the seasonal drop to come.

ice + ICE = Math class

Wednesday ended up being another moist, icy, wintry day that necessitated almost constant defroster use, and I knew the ICE (internal combustion engine) would stay on in my first trip of the day, bringing down the mileage. I also have a couple unavoidable short trips for clients, knocking down the mid-50s mpg for a one-way of my main trip to 44.8 mpg or 5.25 L/100km after 15.9 miles/25.6 km.

I knew on the way home, being a night drive on pure ice again, that it would be great to try some hypermiling with few cars on the road.

After I got home, with the return trip tacked on I was back up to 51.6 mpg/4.56 L/100km. This seems disappointing (only 44.8 up to 51.6?!?), but, of course, the drive straight home without detours to clients is shorter at 12.4 miles/20.0 km, and you can't average mpg just like that.

Which brings us to today's math lesson :-)

Here's a convenient formula for calculating mpg for the last segment of driving you've done, like for calculating the way home of a roundtrip drive. Most people need a ScanGauge, but if your car has instaneous mpg like the Prius, try it out. Of course, you can figure it out on your own, but sometimes it's more fun to be lazy and just use whatever you find on the internet!

It supposes a certain amount of information, like that you wrote down the distance traveled and displayed mpg after the first part of your trip. These are represented by distance1 (in miles) and mpg1 in the formula.

You also need total distance traveled in miles and total trip mpg, respresented by distancetotal and mpgtotal in the formula.

Just calculate the second segment of distance, represented by distance2, by subtracting your first leg from the total distance.

Plug it all in...



And I got 64 mpg or 3.68 L/100km on the way home yesterday in freezing temps!

When it rains, it pou...no, it ices over

Yesterday saw a pretty nasty combination of precipitation, clearly designed by Mother Nature for no other reason than sticking it to low gas consumption.

There was snow in the morning, which I dutifully cleared out of the driveway and off my car. But by the time I had to actually drive anywhere in the afternoon, a couple hours of light rain and sleet had (in)conveniently and thickly layered a sheet of ice over everything in sight, poor Wentworth included.

Since I was on the road to a decent two week tank of potentially 60 mpg/3.92 L/100km, I wanted to keep the streak by scraping the ice manually without running the engine. No problem, I do it all the time...

Nope.

The first scrape lifted a fine spray of ice/snow/non-nomerable wintery substance off the window, but there was clearly a solid coat still below that. More scraping seemed equally futile. I eventually found a crack or two to work into, but even then it was the biggest sheet of ice I'd ever scraped on a car.

An hour and a couple cups of warm water to soften the ice later, I was off, wet, cold, and knowing full well that my Prius' ICE (internal combustion engine, not to be confused with the other stuff) does not turn off as often when there's moisture on the roads. Furthermore, the sleet kept freezing on the windshield, so any crazy defroster antics I might normally play to get the best mileage were out the window, and safety was the name of the game. So defroster and ICE running, I drove "like a normal person" through the 20 mph/32 km/h average speed limits and countless stoplights that get me to work.

I arrived with a mere 45 mpg/5.23 L/100km on the display.

This was actually not disappointing, but a couple things else:

1. Good! It's hard to remember when you can get in the 50 mpgs/4.7 L/100km without trying, and 60s/3.92 when you try, that 45/5.23 is excellent mileage for almost any other vehicle out there, especially in freezing temperatures.

2. Informative. The extent to which driving habits can affect your mileage (and thus your finances!) was not evident to me until a few months ago when I first tried the Prius. I've squeezed out 65 mpg/3.62 L/100km on this same route before, and getting 45 mpg/5.23 L/100km this time shows me how adjusting my habits, but getting there in the same amount of time yields a 44% improvement in mileage.

One other thing - on the way home, not wanting to spend an hour in the mist/rain/sleet/whatever again, I put on the defroster and started scraping. The car was on for maybe 10 minutes or so, and when I got back in the mileage for the 12 mile/19km trip was down to 36 mpg/6.52 L/100km (from 45/5.23 before)!

You can see, if the ice isn't terribly thick, and running your car in the morning before you actually drive just saves you a couple minutes in the name of convenience, or "warms it up", kick the habit. Modern cars really don't need that to save the engine, and you're getting precisely 0 miles per gallon that entire time (it sounds even worse by saying infinite L/100km!).

I also drove "normally" on the way home, since the roads were pure ice at 23°F/-5°C outside temp, save for a little gliding when I could, for a more respectable but still weather-reduced 55 mpg/5.14 L/100km.