Wednesday, May 4, 2011

Fill-up, Tuesday, May 3, 2011

478.0 miles
7.687 gallons

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?


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...

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