Idling vehicles on your nickel…
I happened across this city-owned Ford Expedition idling, unoccupied, with the front windows rolled down as I took my mid-afternoon walk today. I could hear the air conditioning compressor clutch cycling as I walked past. For any of you who might be wondering why our city is spending $7 million more than it will take in during 2011/12 and is forced to get tough with labor negotiations, here’s a prime example of where the money goes.
You might think allowing a vehicle to idle for a few minutes comes at a cost so negligible that it’s hardly worth calculating. I thought the same until this past winter, when I noticed my minivan’s fuel economy dropping through the floor with frequent use of its remote starter. Although I could hardly believe the remote starter could be the cause, I got some information from a friend who is a GM fuel systems engineer and started doing the math.
Costs such as this are calculated by knowing:
- The rate of fuel consumption in gallons per hour
- Length of time the fuel was consumed in hours or minutes
- The price of the fuel in gallons
According to my engineer friend, the rule of thumb for light-duty gasoline engine idle fuel consumption is .5 grams/sec per injector, and that 1 gram/sec is approximately 2.5 liters per hour. Being that the city vehicle was a full-sized Expedition, I will assume it is equipped with an 8-cylinder engine; each cylinder has its own injector. So this forms the basis to calculate the rate of fuel consumption below.
Being the owner of a dog that would have you walk him six times a day if you were willing to take him, I’ve gotten intimately familiar with the time involved. My walk around the block takes me 15 minutes at a leisurely pace. The vehicle was there when I began, and was just leaving as I rounded the final corner. Let’s call it 12 minutes, and ignore the fact that it was there for awhile before I started walking. We’ll use that as the length of time.
The lowest retail fuel price within 1 mile of the spot where this happened this afternoon was $3.739/gallon (cash price) according to DetroitGasPrices.com (The city buys fuel in bulk. I have no data on what the price per gallon is, so I will base my calculations on the retail price.) I have been told that as a municipality the city pays no taxes, which I assume includes the state road tax, sales tax, and the federal excise tax. According to my calculations, based on the data found at the State Attorney General’s website, that tax break would amount to approximately $.529/gallon, for a estimated price to the city taxpayer of $3.21/gallon. (We’ll ignore the cost of labor for filling the city vehicle tanks, the administrative overhead required to purchase the gasoline in bulk, etc., and use just the simple cost per gallon as the price of the fuel.)
Thus, a reasonable estimate of this SUV’s fuel consumption per hour while idling would be:
.5g/s * 8 cylinders = 4g/s * 2.5L/g = 10L/hour or 2.64 gallons/hour.
Using the estimate of 12 minutes, the cost would then be derived as follows:
2.64gal/hour divided into 60 minutes/hour = .044 gallons/minute
.044 gallons/minute * 12 minutes = .528 gallons consumed in 12 minutes.
.528 gallons at $3.21/gallon is $1.70.
If this was the first time I had ever seen a city vehicle idling by the side of the road, I would write this off as being an accident. But there have been many occasions in which I’ve seen the same thing: DPW vehicles, police vehicles, engineering vehicles, etc. On one particular occasion a few years back, police were investigating a crime next door to me, and I observed their vehicles running for literally hours while sitting parked on my street. Curiously, the detective in charge, who arrived in his own personal vehicle (it was late at night) turned his engine off as soon as he arrived.
I can only react to the things that I know about, and I can only report on what I see. Based on just my experience alone, we’re squandering a LOT of money on gasoline in this town. Remember that when you’re asked for a tax increase in 2014.
One final point: the vehicle was unlocked, with all of the windows down, and all of the city worker’s personal equipment was in plain view on the front passenger seat. I’ve had my own personal vehicle stolen not 1,000 feet from the spot where this vehicle sat, which was directly across the street from the site of a home invasion this past winter. Not only does this practice squander fuel, it invites theft in an area that has long been known for it.
If you happen to see an example of this same practice, please send me a cellphone photo.
Update – May 25, 2011
I received the following email from Steve Guitar today:
From: Steve Guitar <firstname.lastname@example.org> Date: Wed, May 25, 2011 at 10:52 AM Subject: Re: Idling vehicles are a waste of taxpayer money! To: Geoff <email@example.com> Mr. Gariepy: Thank you for your recent e-mail that called attention to an occurrence of an idling city vehicle. Please note that this practice is contrary to city policy and will result in a review of related administrative procedures with all city employees. We will exercise appropriate action in this particular personnel issue. Again, we appreciate your comments and the fact that you took the time to alert us in this matter. - Steve Steven J. Guitar Community Relations Director City of Sterling Heights 40555 Utica Road PO Box 8009 Sterling Heights, MI 48311-8009