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Mythbusters: Dirty vs. Clean Car

Trekker4747

Boldly going...
Premium Member
Not sure what the other myths in this episode are, I think there's one involving the "Build Team"/Jr. Mythbusters and alcohol related myths, but the primary myth in this episode is testing whether a dirty car has an aerodynamic advantage over a clean one, the dirt acting like the divits in a golfball do.
 
:lol: what a strange thing to test.
I would be shocked if the difference (if there is any) is even remotely significant in any way.
 
:lol: what a strange thing to test.
I would be shocked if the difference (if there is any) is even remotely significant in any way.

Same. I've often heard that a dirty car reduces efficency, it prevents the air from flowing evenly and smoothly over the car's surface. The preview for the episode shows the mythbusters covering a car in golf ball-like divits in what is obviously the "taking the myth to extreme" part of their "scientific method." ;)
 
That was a fun episode and I really liked the way the Mythbusters dimpled the Taurus to test it, brilliant way of doing it by covering with clay and then after removing it for dimpling and putting the removed clay in a bucket in the back! Awesome thinking on their part and somewhat surprising results!

The drunk myth was interesting, too. I'm not sure why mixing drinks would make the hangover any "better" if they still took in the same levels of alci.
 
Dirty vs. Clean Car: Interesting inconsistency in the results. The premise was that a dirty car's roughened surface would have an effect like golf ball dimples, creating vortices that would let the airflow cling to the surface better and leave a smaller wake in the back, generating less drag. Adam and Jamie made a car super-dirty and got lower mileage instead of higher, calling the myth into question. But when they literally gave the car golf-ball dimples -- first covering it with smooth clay for a control, then cutting dimples out of the clay using an ingenious, simple tool of Jamie's creation -- it got substantially better mileage with the dimples.

I'm wondering if maybe the "Anything worth doing is worth overdoing" philosophy was the problem with the dirt test. Maybe they covered the car so thoroughly in dirt that it was a relatively smooth coating and the vortices weren't formed.

But the success of the dimple effect is intriguing. I wonder if in the future we'll get cars designed with rougher surfaces for better mileage. I doubt it, though. Automakers generally care more about the appearance of good aerodynamics than the often counterintuitive reality. For instance, sportscars are designed to be long and pointy in front and thicker and rounder in the back, even though that's the reverse of the optimal aerodynamic shape (like an airplane wing), because it looks more streamlined. And since we expect a smoother car to be more streamlined, I doubt bumpy surfaces would catch on.

I'm wondering what other means could be used to give a car a sufficiently rough surface. Maybe covering it in a plastic or nylon netting of some sort?

And I liked Adam's explanation of why the heavier clay-covered car registered the same fuel efficiency as the clean car. During acceleration, it would've had considerably lower efficiency, but while maintaining a constant velocity, it was the same. I guess that's why cars have better mileage on the highway -- more time at steady speed, less accelerating and decelerating.


Hangover myth: The myth is that mixing beer with other drinks will make for a worse hangover than beer alone. Mercifully, Kari's pregnancy means she only refereed this one, but Grant and Tory had to suffer for science. Contrary to the myth, both of them, especially Grant, were less hung over with mixed drinks than straight beer.

I suspect the reason for this is simply that they were trying to limit the variables and ensure that the boys drank the same amount of alcohol on both tests. That may be artificial. I suspect that the reason why mixing drinks is believed to be worse is that hard liquor contains more alcohol than beer, so typically, if you're not trying to limit your alcohol consumption to a fixed figure for the name of science, you'd probably just drink more alcohol in the course of a night if you were mixing beer with hard liquor, and that would give you a worse hangover. So maybe they isolated the wrong variable. Of course, that is testing the letter of the myth, but maybe in this case it's taking it too literally, overlooking an implicit step in the process of causation. It's not just "mixing drinks equals worse hangover," it's "mixing drinks typically equals more alcohol intake which equals worse hangover."

Not that I'd want to see them test it again. Tory's reckless enough when he's sober. Keep getting him drunk like that and he's gonna end up doing himself some real damage.

I'm not sure why mixing drinks would make the hangover any "better" if they still took in the same levels of alci.

That's a good question. Wikipedia says:
In addition, it is thought that the presence of other alcohols (such as fusel oils), by-products of the alcoholic fermentation also called congeners, exaggerate many of the symptoms (congeners may also be zinc or other metals added primarily to sweet liqueurs to enhance their flavor); this probably accounts for the mitigation of the effects when distilled alcohol, particularly vodka, is consumed instead.

I'm not sure what the hard liquor was that they were drinking, but if it was distilled, it might've had fewer congeners than the beer and thus produced milder symptoms.


And hey -- we just got through a whole episode without anything blowing up! That's a nice change of pace. And nothing was tested to destruction in any other way either. The only things that got smashed were Grant and Tory. What an atypically sedate episode.
 
Just a couple thoughts about this episode:

- Grant is a total wuss. :lol:
- and I think they should have tried differently sized dimples, at least in the wind channel test, I think that makes a difference.
- Jamie mentioned jokingly "all the NASCARs are going to look like this", which made me think - why don't they if this is actually helpful aerodynamically? Or Formula1 cars, bobsleighs, airplanes, etc., where function is much more important than form? It's not like the effects of the dimples on golfballs aren't widely known...
 
Great episode. I might be wrong but I think I heard them say it had only been two days between their drinking tests, which I don't think was enough time for a proper result. Tory and Grant not being frequent drinkers (or so I gather) they probably had some residual tolerance left over from the previous test, which could easily explain the results. They should waited at least a week.

The car myth was a lot of fun and well thought out. I would like to see an actual factory automobile with dimples and see how it would do!
 
I think it was three days. But you really think two days isn't enough? Generally the rule of thumb is that 0.1‰ alcohol in the blood is decomposed per hour - to still have any traces of alcohol in your body two days later, you'd have to ingest life-threatening amounts of alcohol.

And from personal experience, I'd say that I usually feel absolutely fine after a good nights sleep even when I have a terrible hangover.
 
I think they went about the drinking myth the wrong way, or at least didn't get the right meaning behind the myth.

IMO, the "moral of the story" for that one is that if you drink just beer, or drink hard alcohol before switching to beer, it kind of regulates itself, as the beer takes longer to drink, fills you up, and acts to slow down your drinking somewhat.

When drinking beer before switching to liquor, you're at the partially drunk state, and then end up taking several shots more quickly, not noticing the effects in time. Basically, you're not feeling the effects of the shots as quickly as you can drink them, and you end up out-drinking your tolerance levels.

it's less about the effects of different mixtures at the same levels, but more about how if you're already messed up and then take a bunch of shots before they hit your system, you'll overshoot your tolerance level. Drinking just beer, or beer after hard alcohol, slows that down more, and you're more likely to catch up to yourself at that speed, and know when to stop.
 
This was a fun episode and I enjoyed both experiments. The results of the car experiment were surprising and I didn't actually know how the dimpling did its thing.

I was surprised they didn't edit out Tory's insurance-cringing leap. He looks to be a really rambunctious drunk.


Just a couple thoughts about this episode:

- Grant is a total wuss. :lol:

I thought the same thing.:cool:



Great episode. I might be wrong but I think I heard them say it had only been two days between their drinking tests, which I don't think was enough time for a proper result. Tory and Grant not being frequent drinkers (or so I gather) they probably had some residual tolerance left over from the previous test, which could easily explain the results. They should waited at least a week.

I don't remember what they said but I had wondered as well if there was enough time in between "experiments". Especially as they didn't repeat them. I wonder what the results would have been between beer/beer vs beer/liquor.
 
Well even drinking enough water helps, part of what causes the hangovers is dehydration, so drinking plenty of water would also help keep the hangover to a minimum.
 
I think it was three days. But you really think two days isn't enough?
Alcohol tolerance is a real phenomenon and has no relation to the amount of actual alcohol in the body. I believe it probably has something to do with the amount of stress put on the liver- the liver is progressively able to metabolize less alcohol the more often you drink, therefore it takes more alcohol to produce the intoxicating effect. Or perhaps it is that less alcohol crosses the blood/brain barrier. I'm not really a scientist. But I am an experienced drinker, and I can attest that you will get very different effects if you drink binge levels of alcohol two days apart than you would if you drank them a week apart.

The exact cut-off point is a bit murky. I believe the operant variable would be how long does it take the liver to recover from a binge? I tried googling to back me up but couldn't find a real answer. I'm thinking at least four to five days. Certainly more than two days. In my opinion.

Also, I think it was their reactions that lead me to this conclusion. Grant remarked himself that he seemed to get less intoxicated on the second attempt and attributed it to the mix of beer and liquor. I think tolerance might be a more likely culprit however.
 
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- Grant is a total wuss. :lol:

Except he had no hangover the second time when Tory had a moderate one. If you mean he drank less, he's smaller than Tory and thus could presumably hold less.


I was surprised they didn't edit out Tory's insurance-cringing leap. He looks to be a really rambunctious drunk.

I'm surprised they allowed it, that there wasn't someone rushing in to stop him. I think they were a little reckless with his safety for the sake of spectacle.

I suspect that the reason why mixing drinks is believed to be worse is that hard liquor contains more alcohol than beer

Actually, that's not true. A 12 oz beer, 1.5 oz of liquor, and 5 oz glass of wine all contain the same amount of alcohol.

Uhh, doesn't that prove my point? By that measure, liquor and wine both contain more alcohol per unit volume than beer. So if you take in the same amount of liquid, you imbibe more alcohol if that liquid is wine or hard liquor.
 
It sounded like they had left an EMT behind to monitor things overnight (Kari -who is looking wonderful- seems to suggest it when she leaves for the first night, but yeah it does seem like they were acting up for the camera, the alcohol didn't seem to help that.)

The clay-covered car stuff done was still wickedly cool, including bringing in the design students (who're used to molding cars out of clay) to do the work.

I think nearly everything they did in that myth was perfect and took in to consideration some variables that could be brought against them (like putting the removed clay in the backseat.)
 
Except he had no hangover the second time when Tory had a moderate one. If you mean he drank less, he's smaller than Tory and thus could presumably hold less.

Come on, 6 0.3 litre cans of beer (of undermined alcohol ratio) - please... ;)


Alcohol tolerance is a real phenomenon and has no relation to the amount of actual alcohol in the body. I believe it probably has something to do with the amount of stress put on the liver- the liver is progressively able to metabolize less alcohol the more often you drink, therefore it takes more alcohol to produce the intoxicating effect. Or perhaps it is that less alcohol crosses the blood/brain barrier. I'm not really a scientist. But I am an experienced drinker, and I can attest that you will get very different effects if you drink binge levels of alcohol two days apart than you would if you drank them a week apart.

The exact cut-off point is a bit murky. I believe the operant variable would be how long does it take the liver to recover from a binge? I tried googling to back me up but couldn't find a real answer. I'm thinking at least four to five days. Certainly more than two days. In my opinion.

Also, I think it was their reactions that lead me to this conclusion. Grant remarked himself that he seemed to get less intoxicated on the second attempt and attributed it to the mix of beer and liquor. I think tolerance might be a more likely culprit however.

Hm. I'm not used to getting drunk repeatedly within a certain time period, but I understand what you're saying, and anecdotally I think I tend to agree with you. I have no medical explanation, but I think I can tolerate larger amounts of alcohol if I was drunk not too long ago before too.
 
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