NOTE: The above readout may seem a bit unclear at first glance, but from left to right, top to bottom, here’s what the information means: Instantaneous MPG, Speed, Trip MPG, Distance. I took this photo after a short drive.

By now, we know about devices like the PLX Kiwi and the Scangauge II, but what about those of us who don’t have 1996 or newer cars? How about those who don’t want to spend $170-$300 on instrumentation or prefer to support open-source projects?

Well, the MPGuino is the answer! A few months ago, Darin posted on the forums looking for someone to help him build an open-source MPG gauge for all fuel injected cars. From there, forum member dcb stepped up to the plate and has taken the reigns in a really big way. Nowadays, on release v0.66, the MPGuino is a fully functioning, useful display that anyone with a bit of soldering kills can put together.

Building the MPGuino

The MPGuino is based on the arduino platform, and for it’s tiny footprint I chose to base my build around the iDuino, even though lots of folks use the freeduino. Since the iDuino doesn’t accept the car’s 12v, I used a cell phone charger to convert to 5v and wired directly to the board. Everything else, down to the LCD, which I bought on ebay, is pretty standard to the build. For more of the basic, check out the release one thread.

Anyway, here was my parts list and aproximate prices:
- iDuino: $20
- HD 44780 LCD: $10
- Parts from ratshack: $6-7
- Auto cell charger: $5 (at the dollar store)

Total: $42-43

It’d be a bit cheaper with a freeduino and some parts you might have laying around or found online, but I was trying to slap this together quickly.

Anyway, on to the assembly! The first thing I did was follow the iDuino assembly instructions, posted and annotated by the makers of the kit. However, I didn’t insert the jumper pins because I found it easier to just run the wires I would be connecting through the holes and soldering directly. From there, go ahead and follow the wiring instructions from this image:

My button and component board is a little ugly, but here’s what it ended up looking like:

The next step from here would be to find a project box and try to clean up the mounting a bit, but I haven’t quite gotten to that part yet.

Anyway, with the physical unit put together, go ahead and download the arduino 11 platform to your computer and then test out some of the sample programs. If it isn’t broken (hopefully it isn’t!), go ahead and upload the latest MPGuino software and make sure that everything is working.

That’s about it! The next is to wire it into the car. I disassembled the cigarette lighter cell charger like this and wired it into one of the spare spots on my fuse box so that it would be powered whenever the key was in I or II. From there I simply tapped into the speed sensor wire and fuel injector wire, which I’ll leave up to you to find on your own car, though some suggestions can be found here.

The next step is to power up the MPGuino in your car and figure out how to use it.

Using the MPGuino

Luckily, there’s really not much to using the MPGuino. The first thing you need to do is go ahead and figure out the calibration figures for your car. I’m told that most Japanese makes will use 8204 for the speed sensor and that many American makes will use 10000. However, it’s easy enough to compare the distance on the MPGuino to your odometer in order to see if any adjustments need to be made.

The fuel variable is a bit trickier. Some of them have been figured out, so I would search and then ask, but if your car hasn’t seen the likes of the MPGuino before, you might be the pioneer who figures out the numbers for a perfect calibration. The trick here is to simply keep track of your tank mileage on the MPGuino and then compare it to a standard fill up and make adjustments based on the percentage you’re off from the pump fill.

I’ll be the first to admit calibration can be a pain in the ass, but luckily it’d already been done for me. After that’s out of the way, you can check out your mileage by simply using your three buttons to scroll through the screens. See more about that here.

Personally, I tend to use the instant/current screen the most, and when I’m on longer trips or trips where the sun will hurt visibility on the screen, I use the big instantaneous numbers.

Anyway, this is really were the fun begins. The MPGuino in conjunction with your EcoDriving skills will net some good numbers (see first image).

Limitations of the MPGuino

As of writing (v0.66), the MPGuino has a few issues, the biggest of which is that you have to do all the assembly yourself. That’s not a problem for a lot of us, but for the MPGuino to go more mainstream we’ll have to figure out how to make it more accessible to your average ecomodder.

What’s more, the LCD leaves a little to be desired in terms of readability in the sunlight. However, a solution is currently being worked on.

For more issues, and more up-to-date issues, check this thread or more generally look around the MPGuino forum.

Places for MPGuino Improvement

Luckily, the MPGuino’s faults all play into it’s biggest asset: open-source. Sure, I may want an AFR display, but all that means is that I’ll have to do it or find someone smarter to do it for me. Though limited by hardware (but only to a small degree, platform changes are always a possibility), everything else is up in the air with the MPGuino and anyone can edit the code. If you’re interested, check it out for yourself in the Arduino 11 environment.

Well, I hope you’ll find this useful. If you have any questions or knowledge, don’t hesitate to post in the forums, open-source relies on all you to test and help improve the project!

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This post is part of a series on basic hypermiling techniques, intended to expound upon a more basic description in order to make them more accessible as well as put them in the context of safety and practicality.

Lets face it, this is about as basic as it gets. You’re not going to get better gas mileage if you have no idea what kind of mileage you are currently getting. This task is the first step to improving your gas mileage.

So, how do you track your mileage? Its quite easy, just follow this formula:

Miles traveled / gallons used

This gives you your miles per gallon or mpg.

One thing you must always do is fill your tank completely to ensure accuracy. I recommend filling the tank until it shuts off the first time. Filling past that point can introduce more variation in tank to tank gas mileage measurements.

Logging your information can be done in a number of ways. Many people like to carry a small notebook in their car that they can log their miles and gallons. Some get fancy and use a PDA. Still, others may simply write their mileage down on a receipt and log their info into a spreadsheet or ecomodder’s fuel log once they get home. They are all means to an end. Dating your entries is very helpful as you can see your mileage go up in the summer and down in the winter. It also may help to add notes to your log so you can remember when you did something like pump up your tires more, or track driving conditions if that week the traffic or weather was abnormally bad.

There are some nice benefits to tracking your mileage. Number one is probably being able to monitor driving technique changes. Changing driving technique can alter fuel economy drastically (+/- 50%) for the good or for the worse. Logging mileage also helps with maintenance. If you fill up and see your mileage is oddly low, you know something is wrong with the car and you can have it looked at right away. This may prevent you from being stranded somewhere which is a nice thought, especially in winter. Even if you do nothing else but log your mileage, you are at least going to be somewhat aware of how your driving and environment is effecting your gas mileage.

Is there something more you can do for immediate mileage feedback? Well, yes there is. For those wanting to dive right in, you can purchase a scangauge (or similar device) if your car is a 1996 or newer vehicle. The scangauge plugs into your car’s computer port and spits out all sorts of useful information that can lead to much better fuel economy. For those with an older vehicle you don’t have it quite as easy. But, if you visit our forum we can point you in the right direction. Instant feedback from a mileage device is almost invaluable for tweaking driving style.

So, the quick and easy of it is:

• Track your miles divided by gallons.
• Find a way to log that works best for you.
• If you can, get a scangauge. It is an amazing tool.

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Last week I spent some time with GM discussing their new HCCI technology. After taking their test vehicle, a Saturn Aura, for a test spin, I was very impressed with the heads up display (HUD) that kept track of whether the car was in HCCI or SI mode. Upon returning to the conference room, my first question for the GM techs was whether or not something indicating HCCI mode or gas mileage would show up on the production models of cars equipped with this technology.

I don’t know quite what I expected for an answer, but it certainly wasn’t the one I got. Paul Najt seemed to like the question, and came to the same conclusion that I’ve long had, which is that fuel economy can become like a game. Cars (like many hybrids) with fuel economy displays were mentioned, and some in the room even commented that they believed the knowledge would automatically make people try to get better fuel economy.

More after the break!

I agreed heartily, but I didn’t expect the final answer: “It’s ultimately a marketing decision.” While this makes sense, don’t you think that some control should be left in the hands of the engineers? I mean, GM is asking their people to design a fuel efficient engine to get people through this gas crunch and into the future while still being economically viable, but it’s not the engineers that get to decide if a $10 piece of electronics will be part of that effort?

While I was there I was also told by an engineer who’d recently moved to the US from Germany that in the US people sometimes drive cars that are plain “unnecessary.” Coming from Germany, he and his family were used to a market for much smaller cars, one that GM and its Opel brand is a part of. However, it seems that globally General Motors is in the business of selling what people want, and not necessarily what people need. This mentality is certainly understandable from a business perspective, but I implore GM to consider that if marketing research shows that people don’t want fuel economy displays, it’s because they don’t know how much the feedback could improve their gas mileage.

Seeing that this is one of the things that makes the Prius so popular, and something that other manufacturers are phasing in, I hope GM pushes on with it. Do you think they will, or are ye of little faith (as I sometimes, admittedly, am)?

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Discuss fuel economy instrumentation in the EcoModder forum.

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