MPG Chart Update: June 2008

by Kevin on July 4, 2008

Happy 4th of July, reader! I mentioned yesterday that I was trying to find something relative patriotic and American to write about for today. And what is more American these days than paying for gasoline?

Popular, But Time for an Update

The Automobile Gas Log and it’s associated MPG and price per gallon charts is one of the top set of posts that bring people to No Debt Plan from Google. In fact, if you search “mpg chart” the gas log article is the 6th result.

It’s been four months since I posted that article and I figured I could do an update to see if anything major has changed. Let’s take a look. (Click the images for full sized versions.)

MPG Down

MPG Chart March to June 2008

During the last four months my miles per gallon average has dropped about 2 miles per gallon versus my average for the entire time I’ve been tracking this data. We’ll see if this is significant in minute.

…and gas prices up 24%

Price per gallon March-June 2008

Of course the most dramatic change over the last four months is the price at the pump. In my area gas has gone from $3.13 per gallon to $3.88 — a 24% increase. And it is still moving higher. If I couldn’t before, I can now definitely see why gas inflation is hurting the American economy and the average family out there.

Bad news everywhere, but a positive note

I also track how many gallons I buy each time I fill up. I haven’t put that into chart format as it is pretty consistent and the variation in the number of gallons isn’t important. I could buy twice in the same week if I saw a big drop in prices, or felt a huge increase was coming and just wanted to top off my tank.

However, if I compare March 10, 2008-July 3, 2008 to the previous year, there is a positive note to be added. I’ll count March 8, 2007 to July 5, 2007 as my comparable time period. During the 2008 period, I bought 128.739 gallons of gas. In the 2007 period, I bought 175.953! A decrease of 47.214 gallons of gas.

That’s a huge difference. At $4 per gallon, that equates to over $188. The only explanation I can provide for this change is we moved into our house in September of last year which cut my commute down. But I wouldn’t have guessed over four months I had saved that much gas.

Looking at the numbers it may look like I am buying a lot of gas (and spending a lot of money). I’ve also got to consider I do drive to work lunches. I wouldn’t say I drive a lot for my job, but when I do I get reimbursed for it. It may look like I’m buying a lot of gallons of gas, but when you net out the extra cost and the reimbursement, we only spend about $175 combined every month on gas.

But man, your MPG is dropping!

As I mentioned, compared to the average of all of my driving since I have been tracking this data (2002-present), my MPG for the last four months dropped over 2 mpg. That’s significant, right?

Well, it is significant. If it continued to drop I would start to really inspect the car (or have the mechanic do it at my next oil change). Tracking mpg for maintenance/safety concerns is the reason I started doing this tracking back in 2002. If your mpg drops significantly and your driving habits don’t change, you might have a problem.

In this case I am not as concerned. The MPG drop can be attributed to us not taking as many long interstate trips (high MPG time period). I do a lot of city driving — short commute to work, short trip to lunch with clients, short commute home. That’s my typical day. And I’ve dropped my total consumption of gallons by 47 thanks to the shorter commute.

What about you? Do you track your miles per gallon? Do you know how much you are spending on gas every month? Is your budget under a major squeeze due to gas prices, or are you handling it pretty well?


Blake July 9, 2008 at 4:05 pm

Since I drive a Civic, I’m still able to get around pretty cheaply. I also keep a log of my gas mileage. I’ve got a running average calculation in Excel that keeps me updated on how I’m doing.

More than anything, keeping track of MPG’s is a game to me. I’m always trying to top my all-time record (currently 40.02 mpg). About 75% of my driving is on two-way highways at a cruising speed of 55-60, and this helps A TON. Driving on the interstate at around 70 or doing city driving really eats into my mileage though.

Russell July 11, 2008 at 2:26 pm

My motto is “gasoline is not expensive” I say that everytime I’m riding my motorcycle along a 2-lane road at 55 mph, trying to maintain my 50 mpg economy, and a big pickup truck comes speeding by me at 70mph.

I see very few people treating gasoline as an expensive commodity. It’s readily available. It’s used inefficiently and without planning. (Sometimes that big pickup truck makes a U-turn 3 miles down the road and goes back where it was.)

Maybe it comes from doing some travel in Europe where petrol costs more (in US $) 7 years ago, than it does in the USA today. (European fuel costs a lot more now, but a great deal of that increase is due to inflation’s effect on the US $. Fuel cost has increased about 35% in Europe but it’s cost in US $ has doubled in those 7 years.)

Speaking of inflation, when you look at charts like you realize how (incredibly) US fuel costs have declines for most of the 80 years.

So I say that gasoline is not expensive.

Now Cheez Whiz is another story, the cost of that stuff has gone up to $4 for a tiny jar in Publix. I’ve been getting it for under $3 for years. I still eat it on my nacho chips though. I suppose some of you are now going to tell me that “Cheez Whiz is not expensive”. I guess you’re right.

Russell July 11, 2008 at 2:40 pm

But you asked about tracking miles per gallon. I used to do this thoroughly as you’re doing, with a spreadsheet including every fill-up. Now I don’t keep those records, I do simple math as I fill up.

Buick gets about 25 miles per gallon, that’s 4 gallons per 100 miles. If the trip odometer says 325 miles when I pull into the fuel station, when I start pumping I figure in my head, it should be 13 gallons today.

Yamaha gets about 40 miles per gallon, typical range is 160 to 180 miles. While I’m pumping I figure, 160 miles I’m looking for it to fillup at 4 gallons.

BMW motorcycle about 50 miles per gallon, if I fuel at 200 miles I look for 4 gallons to go into that too.

If the pump gives me a lot more than that, I know there might be some kind of problem with the vehicle.

I won’t detect the 2 mpg difference that you did, but that might simply be you didn’t fill up to the same level from one time to the other. Also ethanol is in many fuels now, and it doesn’t deliver as much power (per fluid measure) as petroleum, so you’re going to suffer in miles per gallon depending on how much ethanol was in that batch of fuel.

Gas Mileage Chart December 8, 2008 at 9:54 am

It is possible to improve your MPG with an existing car but when you are ready for a new one the right choice can make a big difference.

Unless you had real bad driving habits (joyrider?) it pays off to be careful not to accelerate too hard from a standstill. Also keep an eye on the traffic situation so you can predict and avoid braking.

Just keeping records like you do is a crucial first step to getting better fuel economy. Great inspiration!

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