On being a fuel nerd

The wind in your hair, the sun glistening off of the metallic paint, the rumble of the exhaust as the pistons reciprocate inside their cylinders and control the repeated explosions of atomized flammable liquids to propel you across the country. These things are the essence of being a gear head. Unfortunately they are not at all what this post is about... Instead what I'm going to do is transition to the nerdy world of tracking your fuel consumption. As much fun as it is being out on the open road without a care in the world, when your Low Fuel light comes on you may pause and think for a moment what actually goes into making you move.



"I just give the gas man my credit card once a week."
Pretty much since I started driving back in High School, it always seemed normal to me to keep track of how much gasoline my car was using. When you're living on part time wages earned during the summers, knowing if that $20 that you found in your jeans would get you to the lake and back was important. As I grew up got older and started talking to a variety of people I was surprised to learn that many people had no idea how much fuel their vehicle used, how much their driving cost them, or even how to figure it out! And some people really just didn't care to know.

If you want to be one of those people who simply doesn't care about fuel consumption, that's fine, you're not alone. There are plenty of people who, when asked about their gas mileage, would simply answer "I think it's pretty good." Sticking your head in the sand can save you a bit of effort with a calculator, which is good if numbers scare you.

There are, however, a number of reasons to know how much liquid your engine is sucking out of the tank. The first is so you know how much money is being sucked out of your wallet. Not only does knowing how much you're spending on fuel help you budget appropriately, it also helps you keep track of any changes you make. If you want to save a bit of money reducing your fuel use is a step in the right direction, but you won't really know what has been effective and what hasn't unless you keep track of it.

Another reason why keeping track of your fuel consumption is a good idea is that it's a useful diagnostic tool. Often times a sudden change in fuel consumption points to a problem with the vehicle, which can be fixed easily if caught early. An incorrect fuel mixture caused by failing parts can eventually lead to engine damage if left too long.

Finally, bragging rights. The horsepower wars have been waged for decades, with each manufacturer trying to boast higher figures than the rest, but the fuel economy wars are quickly catching up. The Toyota Prius, Honda Insight, Smart, and other cars which focus on fuel economy as their biggest selling feature have been going strong for several years now. Knowing what the fuel mileage stickers on the cars actually mean and how to compare them will give you a leg up when shopping for your next vehicle.

So there's math involved, huh?
The actual work behind tracking your fuel consumption fairly straightforward and effortless. All you have to do is write down how much you drive (in miles or km) and how much fuel you put into your vehicle (in litres or gallons). That's really all there is to it. The best way to do this is to reset your trip meter every time you fill up, and write the figures down in a little notebook (or on your phone or computer) that you keep in your car. In order to be accurate you should fill your tank to the same place each time (whether that's to the first click or until the gas is almost overflowing out of the filler neck) and try to use an entire tank of gas before refilling. These will give you the best average for that tank of gas, but over a longer term your average will be accurate even if you don't do these things, as long as you write the figures down every time you get gas.

Once you have your gas amount and your distance driven, you can divide one by the other to get a fuel consumption figure. How you do this depends on where you live and what units of measurement you use. If you measured in miles and gallons, divide the first by the second to get Miles Per Gallon (MPG). For example, if you drove 253 miles and then refilled with 9.7 gallons, your consumption is 253/9.7 = 26 MPG. If you use a more logical system the metric system and record in kilometres and litres, divide the second by the first, and multiply by 100 to get L/100 km. For example, if you drove 407 km and refilled with 36.7 L your fuel consumption would be 36.7/407*100 = 9.0 L/100km (this works out to 26 MPG).

A note on units: I'm assuming that people using MPG are using US gallons, which is equal to 3.78 L. There is also the imperial gallon, equal to 4.54 L. While it doesn't really matter which one you use (obviously you'd use whatever is displayed on your gas pump) it should be noted that MPG(US) figures won't be directly comparable to MPG(imperial) figures. The Canadian EnergGuide labels placed on new cars sold in Canada state fuel economy in MPG(imperial) and L/100km, whereas EPA labels in the US give in in MPG(US). This makes it seem like Canadian vehicles get better fuel economy than American ones, when they do not.

Another note on units: some people like to use km/L instead of L/100km, probably because it's an easier mental shift from MPG where higher numbers are better. This is not a standard way of doing it, so if you use that method you might have a hard time comparing it to other cars.

Modern Conveniences
While writing down your fuel and distance in a notebook and calculating your fuel consumption using basic elementary math (gasp!) was common in previous decades, there are some tools to help alleviated us of this chore today. For one thing, many cars can tell you their fuel consumption directly as you drive. One caveat with this method is you should be aware of what averaging period is being used to calculate this. On some cars resetting the trip meter will reset the average fuel economy, whereas on others it has to be reset manually. These are convenient, but they won't be as effective at tracking changes in fuel consumption due to mechanical issues, so I suggest doing it manually at least once in a while to confirm the numbers.

Another handy tool available online is Fuelly. Fuelly is a website which allows you to set up your car profile and keep track of fill-ups and distance driven. It will calculate your fuel mileage for you, both per tank and an overall average, keep track of how much you spend on gas, and most importantly it will allow you to compare your fuel consumption to other people with the exact same vehicle. It's a very useful site to check when shopping for a vehicle, as it will allow you to check each vehicle your interested in and how it shapes up in real world conditions, compared to similar vehicles. The site allows you to track both cars and motorcycles.

Lastly, there are a number of apps for the iDevices and Android based platforms which will carry out these tasks for you. I'm not going to go into any detail on any of them here - if there are any you really like feel free to leave a comment. If you're interested in reducing your fuel consumption there are many blogs available online regarding hypermiling. Mr. Money Mustache recently posted about some Fuel Saving Hacks, which is worth checking out if you have a road trip coming up.