Tracking MPG based on Month & Lifetime averages has been a common practice for us. Grouping data like that makes sense. What hasn't captured much attention though is the perspective of Seasons. (Months grouped based on like temperature ranges here in Minnesota.) So, I took a stab at it today. With over 4 years of data (lifetime spreadsheet) already gathered, it always intriguing to see what crunching the numbers results in. Here's what I came up with: .
My travels in San Diego and throughout Southern CA yield a similar seasonal variation in MPG. Though we don't get the temperature extremes, 60F is cold and 80F is hot to us weather wimps (and damn proud of it!), we do get the "winter blend" gas - and then the MPG goes down. So, in the effort to save emissions using the winter blend, everyone gets about a 10% drop in MPG - so we all burn more gas. Go figure.
I've seen a similar similar variation here in eastern Washington. The biggest change I noticed was when I changed tires in August 2006, but the seasonal variation is still there.
So far, I'm not off to a good start this (winter) month. I only had 2 commutes to work, and neither was at commute time. To confuse matters more, the temperatures have been lower than normal. And last month was a complete loss for a routine, since I was away from work for most of it. I have noticed a pattern emerging though. With the upper blocked entirely and about 70% for the lower, the effect seems to be the system acting as if it was 20 F degrees warmer. Whatever the case, I'm excited about watching (and documenting) how it plays out.
