Aerodynamic Tail Makes Geo Metro Even Cooler

[MetroMPG], an environmentally friendly car enthusiast from Ontario, added a tail to his car to increase gas mileage. This 1998 Pontiac Firefly is a sibling of the cheap and popular Geo Metro. He had already done some work to cover a portion of the rear wheel wells to reduce drag. Using cardboard, duct tape, and an aluminum frame he extended the rear of the car by around six feet.

The results are pretty impressive. His extensive testing can be seen in the video after the break and reveals a Miles Per Gallon increase of 15.1% at 90 km/h to get to 64 MPG. The tail is removable but we’re thinking it’s a pain to keep relocating the tail lights from the original body to the removable one.

Now we’re wondering if someone is doing this to our Smurf-blue Metro that we sold to the junk man for $100 back in 2001. It ran great, if you weren’t caught in the cloud of blue smoke coming out the back.


[Thanks Darin]

77 thoughts on “Aerodynamic Tail Makes Geo Metro Even Cooler

  1. Impressive that he did all the testing and didn’t just assumed, and interesting that the shape could have so much effect but so many cars still ignore it in their designs, and I mean designs of cars that are labeled green, not just the designs of your hummers and such, although, you can’t make a tail as long as this one since you can’t park in many many places then, and people like to be able to park their car :)

    But why didn’t he use black straps to attach it? I mean why go through all that trouble and drop the ball like that?

    @sasdface You do realize how light aluminum is right? And even if you dropped this thing from space the tubing would probably not penetrate the body of a car.

  2. Yeah we’re all basically doomed if a tapered behind and covered wheel wells (Like old Citroen’s) can make such a drastic increase in efficiency. There is too much ego linked to our cars.

  3. I don’t understand why attaching something to the back of the car would make it more aerodynamic? Wouldn’t moding the front of the car be more effective? Maybe I need to read up more on aerodynamics..

  4. Granted this is a quite functional and obviously useful “hack”. However it is now the most retarded looking vehicle on the face of the planet and i wouldnt be caught dead in that. I would drive a prius before i would drive around in something that looks that weird. Nice “hack” though, seems SOMEONE is doing something to beat the oil giants.

  5. @nave
    The problem is that most consumers would never buy aerodynamic cars. Manufacturers put a huge effort into convincing the public that you NEED an un-aerodynamic slab of an SUV to get to the mall and back in style. Most people were stupid enough to buy into it and now it’s hard to reverse that meme and suggest that goofy looking aerodynamic cars are cooler than goofy looking blocks with wheels. (Scion xB, anyone?)

  6. @moo

    The rear end of a body is typically more important than the front end – at subsonic velocities.

    @whatnot – no black straps because it’s temporary – he was simply testing for gains using fast/easier cardboard :)

  7. The mythbusters have shown you can dimple the car like a golf ball for about a 12% increase in your MPG without going having to to resort to useless empty extensions of the front or rear of the vehicle. Granted, a dimpled car is not for everyone. But it does not require restriping every parking lot to accomodate 6ft aerodynamic extensions either.

  8. @BuzKill

    Many people drive a full-length pickup, the f-150 is the most common vehicle in the USA.

    This isn’t even that long really, and you could design it to fold up for parking and low speeds.

    I commend this, great hack (and it got me back to ecomodder, a great site.)

    Re: “mythbusters”; don’t forget that you can add the 15% (this was 15% on top of a full undertray and a kammback!!) onto the 12%, more is always more.

    Also you could angle back the roof-line with a chop to be lower in the back, then use a shorter extension.

    I wouldn’t argue with 65mpg at 55mph (average in back to back 2-way testing), that is great.

  9. This, much like the Mythbusters test, is primarily a “proof of concept”. Neither is particularly practical using the tested methods. However, the concept is solid and can be scientifically proven and now (hopefully) the engineers will work on adapting them into practical solutions. (Retractable tail/fins? Adapted painting techniques to mask a dimpled exterior?) As far as high efficiency vehicle technology goes, the industry is in it’s infancy.
    One would have better luck adding unsightly modifications to vehicles in Europe, where gas is much more expensive than here (not to mention they lack our American ego about cars).
    That being said, offer me a 80 mpg hybrid with 5 star safety ratings and a reasonable amount of low-end torque and I would definitely own one, no matter how unsightly it may be. It would be fairly easy to repel any heckles with a response of, “It gets 80 miles per gallon and does 0-60 in 8.2…piss off”.

  10. I agree with the “blocks on wheels” argument. I dont understand why when driving on the highway, i see tons of big ass SUV’s with only one person in them. Now i could possibly see if you had a crowd to carry around, but one person?? I also dont understand how the Scion XB is selling, its ugly as shit. Not to mention the newer designs of cars are ALL blocky and “retro”. They DO need to make them more aerodynamic. Its all likely a ploy to keep oil sales up…

  11. Europe, where gas is much more expensive than here (not to mention they lack our American ego about cars).

    Alfa Romeo

    Plus billions in illegal arms sales to
    every enemy on the planet and starting
    all the major wars in the last 100 years.

    Yeah, you Euros are nice bunch…

  12. There is still room for improvement in tail shape (and comments). The fluttering tells (short strings) show where he is losing laminar flow on the bottom of the extension. That part needs to stay wide while the top might be able to drop sooner (and be shorter). Who is going to be the first to make an inflateable/ retractable version for a typical vehicle?
    @ “children” : lose the attitude

  13. Longtail designs like that were used in the 60’s to get the last ounce of top speed from the cars which raced at Le Mans. The streamlining came with a handling penalty though, because the shape produces lift.

    That aside, it’s the most retarded vehicle I ever saw and living proof that stupid hippies shouldn’t be allowed to own vehicles. If he’d put a V-8 engine in it I might be impressed.

  14. hmmm i know this is using quite light materials but with its large surface area meaning gravity will take place which will therefore be adding much more weight, i am pretty sure the areodynamics are been componsated by weight making this hack well useless and ugly and a risk for cars behind e.g it falling off? also its not like that modle has much drag anyway it would be more usefull to mod its front so it cuts through particles and colides with less.

  15. Manufacturers generally do these tests with their cars to make them as efficient as possible for the materials alloted. This is not likely true of a Geo Metro, which is like a sized-up matchbox car with a lawnmower engine.

    If you do this to a modern ‘green’ vehicle, especially the electric ones, you will ruin the laminar flow and increase separation and turbulence more than improve it.

    That said, good job with the thorough research.

  16. @marshall plan
    if you’re going to bring your shitty political trolling into the discussion, then gtfo. i don’t see you mentioning the countless number of people the US has killed, from its own citizens (lack of affordable healthcare, war on drugs, police brutality) to countless “non-wars” (China 1945-46 1950-53, Korea 1950-53, Guatemala 1954 1960 1967-69, Indonesia 1958, Cuba 1959-61, Congo 1964, Peru 1965, Laos 1964-73, Vietnam 1961-73, Cambodia 1969-70, Lebanon 1983-84, Grenada 1983, Libya 1986, El Salvador 1980s, Nicaragua 1980s
    Panama 1989, Sudan 1998, Afghanistan, Iraq).

    If you want to talk about arms dealing, why not discuss how the US is directly responsible for creating and financing what is the modern-day Taliban?

  17. @jeditalian
    seems like a fair price
    my friend’s geo metro would stall if you tried to go up a steep hill and then turned the air conditioning on

    3 cylinders of pure muscle! it can sometimes outrun a motorcycle! it’s almost guaranteed to be faster than a bicycle! GEO METRO!

  18. Why not wire up some sort of auxiliary light connector for the rear tail lights. Perhaps a trailer light wiring harness would do the trick, could then get a second set of tail lights.

  19. Never really seen the Geo Metro or the Scion XB before and I have to say; what the bloody hell? people actually thought “hey that looks like a nice car” and bought one with their own money? I’d rather have a Morris Minor than one of those two cars!

    Extendable tail, how about using fabric for the cover with movable struts so the tail can extend/retract at will, like this BMW concept:

  20. If you read up he did have a truncated tail on it (otherwise known as a kammback), this 15% improvement is after the kammback.

    I see a lot of haters. He did 3 tests with, 3 without, and a further 2 tests with (each ‘test’ is run both ways.) I don’t see how he is doing it in an unscientific manner.

    Facts are that you can improve the aerodynamics and gas mileage of most road-going cars, even hybrids.

    The weight does not make a difference to the economy on this scale (~15 pounds of aluminum, cardboard, and plastic). Weight makes a difference on acceleration, once the mass is accelerated it isn’t a problem. Unless you notice the difference in your cars’ fuel consumption between a 3/4 tank and 1/2 a tank (approximately the same weight as this mod), you won’t know the difference, except the car will use much less fuel and have better hihg-speed handling and acceleration.

    Interesting how the haters shut up when fuel goes above $4 a gallon ;)

  21. How many of you are still living off of your parents? When you have to choose between getting your son a coat that fits for winter, or paying the propane bill, getting an extra dollar out of a super-cheap car is damn f*cking important. I’m in that situation. Isn’t it past your bedtime? Oh yeah, *click,click* get off my lawn. ‘tards.

  22. Whatever your viewpoint of this project, this guy thinks out of the box, he has the skills to do some nice mock-up work, and he’s collected some data that shows benefit for the mod he tinkered with.

    What’s to complain about here?

    In the last year, the US has *doubled* the amount of currency in circulation (printing presses gone wild.) What this means is that when the recession is past, inflation will begin. Even without the effects of peak oil, the dollar value of a gallon of gas is going to shoot through the roof.

    If gas gets to 6 or 7 bucks a gallon, and a cardboard tail cone will get me a 15% discount, guess what…my vehicle will get a tail cone. End of story.

    My guess is that you are going to see more of this kind of thing.

  23. The results of this augmentation is interesting, but unfortunately the whole thing looks hideous. One of the biggest selling points of any car is aesthetics, which often comes at a cost aerodynamics.

    On a side note, what really bugs me with “futuristic” concept cars, particularly the ones that are meant to be fuel efficient, environmentally friendly, etc, is that they are fucking ugly. Surely, if an industry wants to break free from petrol dependence, at least try making it look attractive as well.

  24. This is all well and good, but the question is how much of an increase will there be once you cover all of the state and federal regulations to make it street legal? There are bumper laws and other considerations such as location of lights. It might work just as well, but without following all the rules, it makes this more of a test run than anything conclusive.

    @Whatnot “You do realize how light aluminum is right? And even if you dropped this thing from space the tubing would probably not penetrate the body of a car.”

    Motorcyclists and bicyclists might take issue with your line of thinking.

  25. And just how stable this thing is going to be when you have a strong wind gusting from the side? I would assume that it’ll have a strong tendency to change lanes all by itself and depending on the wind direction it’ll end up as a hood ornament or in the ditch.

  26. @Andy, surface area has nothing to do with gravity

    @Kevin, you can make a dune buggy legal, it’s mostly about lights, horns, and plates. That being said, you can register a car as a kit car and get away with crazy mods. I’m not sure what your point was about motorcyclists and bicyclists though.

    @TheFinn and other people objecting to this test, this is clearly a proof of concept

  27. ya I sure when you make a hard left and wipe out some people on the side walk the money you saved on gas will be more than the money lost in the lawsuit.the other big problem with this is practicality you have a hard time using the hatch for anything with that attached. and a huge blind spot. the airstreamers of the 30’s was not the most practical cars. you forget the modern car is a compromise. If you realy cared about fuel use buy a bike or learn to drive.

  28. So, can this be made inflatable, or at least retractable like a convertible? Nobody would need or want this thing in city driving, but if you could pop it out while on the interstate…

  29. @nubie and others.

    3 tests show a difference in MPG, but I’m still unconvinced that he is doing this correct. Here are a few things that immediately jump to mind.

    1) Shifting the weight could bring up the front bumper enough to allow under the vehicle giving it more lift. Sure better gas mileage at the cost of traction.

    2) Plain old lift of the tail, once again trading MPG for traction.

    3) Subtle changing in driving pattern since this was not a blind A/B testing. Maybe if he had others drive the car with some quick training to see if there was a statistically significant difference between the two tails.

    Honestly I’m betting that he is trading traction for MPG and this is probably a dangerous trade off for highway speed. This is why a chopped tail was the preferred design as it had almost identical drag reduction without the problems of weight or lift.

  30. eric: I think you’ve missed the point. The mod may reduce traction a little (probably insignificant, it will be ~1% of the weight), but that’s only because it’s a custom mod. Putting shopping in the trunk would have a larger effect.

    The demonstration is showing the application of rear end tails in improving the aerodynamics, the weight distribution (/wheelbase) of the car is irrelevant and could be changed and compensated for easily by a manufacture.

  31. @Alias

    The weight of the mod is small, but it’s affects on the lift ( or drag ) of the vehicle, at highway speeds, is not insignificant if you take his calculations at face value.

    Long tail vs chopped tail has been explored by manufacturers before and it’s been shown that a chopped tail provides a vast majority of the drag reduction without the problems on lift and handling. It’s not like some vast conspiracy to hide the truth is out there, it’s been done before.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.