Inexpensive MPG Modding

[basjoos] modded [via] the body of his ’92 Honda Civic – and managed to improve his fuel efficiency from 50-60MPG up to 95MPG for about $400. Even more interesting is the SuperMID (Translated) that he added to the car to monitor his fuel efficiency. It’s based on an ATMega8 that reads the CAN bus and displays realtime MPG information an a character LCD. The SuperMID is popular for Prius modders because the on-board display maxes out at a paultry 99MPG. If micro-controller’s aren’t your thing, [Atilla] put together his own CAN bus decoder and ported his code to a Zaurus SL-C700. He even added voice feedback notification for certain data events.

70 thoughts on “Inexpensive MPG Modding

  1. However, you must also keep in mind that a cars engine and transmission tend to provide peak MPG at a particular range of speed. Since the fuel efficiency wanders with speed because of the engine speed/gearing AND aerodynamics, your statement is an oversimplification. A large portion of the paneling appears to be made from corrugated plastic and aluminum, and the glass hatch has been removed, which reduces weight as well.
    A “straight down” shape is not good either, unless the body leading up to it forms a “Kamm” back, which is basically a teardrop-type shape with the end cut off. This is done because it is found that, if you form enough of the airstream, it will follow that shape without the speed. So yes, you could remove SOME of that end and get similar results, but it does have an advantage over the original rear hatch.
    Volkswagen used to show off that their Jetta, because the trunk led the car to a more narrow tail, had better wind tunnel results than the hatchback Golf.
    OTOH, I agree that it’s ugly :)
    I’m just waiting for the Aptera to get sold up here in Canada…. 150+MPG plug-in hybrid that I could actually afford.

  2. @45
    >except that they don’t, they make shapes very similar to spheres

    Umm no – surface tension causes them to go from spheres at small diameters to hamburger type shapes at somewhat larger diameters and eventually annular rings as big drops fall apart… USGS

    If aero were the only consideration for fuel economy – you’d be totally right… But that’s not the case – I mean, one would assume the engine speed changes (and efficiency) at all of those different velocities :P

    Seriously, why do people think a small amount of weight is such a big factor… Given the materials, and the parts removed… It’s no different than having an extra passenger (if that). I can say from watching my scangauge – one extra passenger doesn’t kill 30mpg off my car.. In fact, it’s outside the realm of significance…

  3. @16 (pt 2) in addition to “driving lightly” this man has a hand throttle and a microcontroller to monitor his actual realtime fuel consumption. He is not just driving, he’s being super careful and seems to have devoted as much (though from the looks of the vehicle…way more) time to perfecting that aspect of his fuel consumption. You can save a surprising amount of fuel by altering your driving habits in such a way.

    I think I buy his figures. He’s trying very hard.

  4. @21: Weight mainly only impacts the energy needed to accelerate. If he’s doing mainly freeway driving the added weight won’t matter much, but the reduced drag sure will. (For the nitpickers: Yes, weight increases rolling resistance somewhat, but this is a relatively small issue — especially if he’s running high tire pressures.)

    @33: Hybrids are meant to improve city mileage, not highway. On the highway there’s no braking energy to recover. So they’re not “BS”, they’re just intended for a different application.

    @35: How do you define “good”? My aero-style Crown Vic is lucky to top 22 mpg. I don’t consider that anything to write home about. There are pickup trucks that do better.

    @38: My bad. I should have said “at the drive wheels,” not “at the rear wheels.”

  5. @37 I said nothing about a “steep drop”
    @54 I get almost 28mpg on the highway at night, I found it was slightly more economical to not use cruise control for some reason

  6. according to wired, this guy is a 55 year old EET, who just eyeballed everything, and the 95mpg measure is just when hes on the interstate going downhill on broken in tires and idling / coasting and all this other impractical stuff. the real measure is around lower 70ish i believe.

    honestly he could do a better job with some fiberglass and some body putty.

  7. This is such a load of crap, if it was that easy to increase and inexpensive to increase fuel economy do you not think an auto manufacturer would simply do it considering the billions of dollars at stake?

    There is a very significant consumer demand for fuel efficient vehicles.. Why else would anyone else in their right mind drive a Mercedes Smart Car? Or hybrids..

    If this nut thinks for $400 he can crack some fuel economy secret he’s obviously siphoning gas from his neighbors and ingesting large quantities in the process.

    Considering the last three US automakers are in a downward spiral and facing a painful death do you not think if increasing fuel economy almost %50 was that simple and cheep they wouldn’t do it, it would save them overnight. Heck companies like Toyota and Honda would be all over this.

    This guys a fraud, his claims are bogus, and anyone who believes him is a moron.

  8. I really like the mod. Even if it doesnt get the result of 95mpg, this guy spend time thinking about how to make his car more efficient and that is a good start.

    And yes, reducing has been done before, a long time before. In 1921 Rumpler presented a car with 0.28cd. Doesnt seem to good today, but back then it was only a third of the resistance many other cars had.

  9. @57 – That made me laugh :p

    He didn’t crack any secret – it’s well known that streamlined shapes are far superior…

    Yes, mfr’s have picked up on it… The VW 1L project, for example (235mpg)… Or the Aptera as mentioned earlier (while it is a hybrid – it’s still 150mpg). The prius does in fact share a similar design (it’s more kammback though). And the best tank ever recorded for an unmodified Prius is somewhere around 110mpg. Driving technique + aero + mechanical… It’s no secret ;)

    The problem comes in driving and parking… Long cars don’t work well in an urban situation – especially if you need to parallel park… And even when done well – many people still think they’re dead ugly.

    And the unfortunate fact is – despite oil prices – 50%+ of the new car market share in the US is… SUVs and “personal trucks.”

    Too bad Kei class cars aren’t sold in the US

  10. its not possible. the highest mpg possible from one gallon of gas is about 100. with an internal combustion engine the highest usable energy from one gallon is 50mpg. unless he invented his own engine hes lying.

  11. The whole is greater than the sum of it’s parts. Combining aerodynamics with hypermiling and the plethora of good suggestions mentioned in this thread should achieve 95mpg+ without difficulty.

    I like the paneled underside idea. It is well overlooked. Out of sight, out of mind is quite true. It also should help prevent oil/engine fluid spillage onto the road and thus into the environment. In fact, how green is any car that doesn’t alleviate such spillage?

    If the numbers can be properly proven to Honda or another entrepreneurial manufacturer, and just the major determinants of drag reduction are used, a chance to profit in the short term from mass producing mod-kits for select vehicles is tempting.

    Aesthetics can be incorporated along the line to assuage the libido factor.

    Parking is only an issue if you don’t know how. I drive limousines part-time and parking stretches in Seattle hasn’t presented any problems for me.

    I submit that long-haul trucks could save the most fuel nationwide by incorporating better aerodynamics. The long stretches of freeway, less braking, etc…

    As concerns the bigger picture, I submit that the greatest problem with over-consumption of gas and oil actually comes from the fact that people are inordinantly ‘married to their car’ due to the lack of affordable housing and self-sufficient communities which force people to drive excessively to their places of work and shopping. This is due to ‘social engineering’ designed to secure political power in the hands of a few. This is done by surreptious manipulation of the (OH-SO-BORING-I-CAN’T-PAY-CLOSE-ATTENTION-TO-THE-DEVIL-IN-THE-DETAILS!) building codes and zoning regulations in America (the biggest consumer of oil and gas ordinarily) that disallow communities (powerbases) to form and solve problems on a local level.

    Sorry for deviating off topic a bit. I actually limited myself this time.

    Kudos to the developer for making the efforts to solve the gas consumption problem. As for the unbelieving detractors in this thread…let he who is without BS cast the first turd.


  12. Great article. There are products out on the market that have been proven to increase fuel efficiency while reducing emissions and wear on your engine. is a website that has information on a product that will do just that.

  13. My 1990 crown victoria boxbody gets 35 mpg on highway with 5 people aboard (cruise set at 55mph) . Things i did to improve milage are nitrogen filled tires, synthetics everywhere removed landau top ,aero wheel covers.

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