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What are the pros and cons of plastic cars?

by wcunning CNET staff / June 6, 2007 6:57 AM PDT

In my recent column, The plastic transparent car, I wrote about increasing use of plastics in car body panels. Would you buy a car with a plastic body?

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Plastic cars
by msd1107 / June 6, 2007 2:14 PM PDT

There is nothing new about plastic (or composite material) cars.

The original Lotus Elite from 1957 used an almost 100% plastic construction. And the Lotus Elan from 1962 used a plastic body over a metal backbone chassis.

Composite materials provide many benefits, especially in designing controlled crushability for absorbing the impact loads in an accident. Conversely, a metal body deforms in a finite set of deformations, leading to non-linear g-forces applied during deceleration.

The ultimate is seen in F1 technology, where carbon fiber composite structures provide the ultimate in safe deformation and passenger protection.

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Electrical Engineers Perspective
by JBL is Junk / June 20, 2007 2:07 PM PDT
In reply to: Plastic cars

I'd rather be hit by lightening in a solid Faraday Cage than one with plastic holes in it!

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You won't be hit...
by edge_bit / June 20, 2007 2:18 PM PDT

First of all, you're in all-plastic. Unless you're atop the highest mountain in a storm, you're not very likely to be hit at all.

As well, if it's grounding you want - the metal roll-cage will be more than sufficient. It should suck up all of the charge as it is higher up than you.

I'd like to see this tested, however. That one "Mythbusters" episode was interesting.

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edge_bit and Mythbusters (Cars made of plastic)
by Daibad / June 20, 2007 10:02 PM PDT
In reply to: You won't be hit...

Sorry edge_bit that you found Mythbusters 'interesting' I have seen only two of their programmes and they wererubbish -the last one was to 'prove' it was not possible tobe sucked out of an aircraft if the fusalage is breached. They factored in many aspects to be encountered in such an incident BUT they completely forgot (or was it merely omitted?) the effect of a 500mph wind passing the fracture. True ALL the experiment was conducted on the gropund but have you ever held a piece of paper in your hands (tried to read a map) beside an open car window -at perhaps 40 mph? Need I say more?
David Courtney.

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True Scientific Research
by fritzbrown / June 21, 2007 12:35 AM PDT

Of course, why didn't the Mythbusters just drive a car down the freeway with the window open?
That obviously constitutes research that isn't "rubbish"

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Myth-Busters
by MrGadgetman / January 29, 2009 12:16 AM PST

Yeah..., Mythbusters always gets stuff wrong. I don't know who they are consulting with when they conduct those experiments.

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Plastic Cars in the DESERT.. BURN ME OR MELT AWAY!
by vgl1979 / June 21, 2007 8:45 AM PDT

well, first of all.. I am tired of being an EQUAL victim compared to the victims of 9/11 with METAL cars here in the DESERTS of Arizona burning me all over before the air conditioner to kick in. It takes approxiametely 30 minutes for the inside of the car to cool down and everyone winds up home by then. Plastic cars, how thick is the plastic, will the PLASTIC melt in 109+ degree C weather? Will it cool faster?
Would the price change? Less , more?
Overall, I believe it would be a *GREAT* idea to have plastic cars... and I'm still waiting for more SOLAR CARS.. whats up with all of this?

sincerely,
DENISE MARIE KING
I.T. INDUSTRY MANAGER
vgl(viriigrrl) of EFNET
http://members.fortunecity.com/cryptik/recipe.htm
http://members.fortunecity.com/cryptik

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Injection mouldings
by colin1935 / June 21, 2007 9:32 AM PDT

Just think of all the items in your homes that are injection moulded thats far higher than a 109d operation.
You are missing the point Plastic =fibreglass buses,trains lorries (most likly in aircraft also) been uses for over 50 years

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Plastic cars
by Rick1600 / June 20, 2007 10:49 PM PDT
In reply to: Plastic cars

I prefer to call them Polymer. I own a 1994 Saturn one of the best cars I've owned. I've had a few cars in my time. They do not rust, clean & shine , wax, is a breeze!!! No cons!!

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Plastic vs steel, etc.
by deboernk / June 21, 2007 1:42 AM PDT
In reply to: Plastic cars

Plastic is made from petroleum. Steel is not.
Steel is being recycled all of the time.
Manufacturing is in place to do that.
Rustproof steel alloys are being used in vehicles today.
Lightweight steel alloys are available and being used in vehicle manufacturing right now.

Plastic has been used in vehicle manufacture for quite some time and that practice will likely continue. More plastic seems to get added to vehicles as time goes on. But I see no reason to go overboard with that practice.

Some plastics are recyclable but many are not. Depends on how they are made and what the market is for recycling that particular type of plastic. Also, some plastics have addatives that are not easily recycled.

Use steel where it has advantages and plastic where it's benefits are the strongest.

I see no reason to use a lot of plastic in vehicle manufacture.
And, it uses up petroleum resources that could probably be better used elsewhere.

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recycling practice
by batman823 / June 21, 2007 2:45 AM PDT
In reply to: Plastic vs steel, etc.

Most of the plastics today are recyclable. Most of the plastics used by auto makers are made from recycled plastic or recyclable plastic. If they don't use plastic, they use cheap, flimsy sheet metal or some alloy. Any steel alloy is not lightweight. It's still steel. They just mix it with copper, nickel, tin, or ather metals to make it stronger or more flexible.

Today's use of metal is useless. Plastic would provide the same protection that the sheetmetal provides while reducing the weight. This actually does not increase the amount of petroleum used since they are made from recycled plastics.

True, andy77's 20+yr old car is made of stronger metals. But 99% of the cars out there today that use metal siding offer no more protection than the ones with plastic or fiberglass siding. In fact, composites and fiberglass are lighter than steel siding and stronger. Some can crack or become faded and brittle over age though. So there pros and cons to both.

Even if a car is made with new plastic, the car is still lighter. If the car only improves by 1mpg, over the life of the car much less petroleum is used for fuel.

The cage and frame of the cars could be made out of some foam-infused aluminum compound or other composite that is actually stronger than steel. But since steel is more readily available and cheaper than those kind of composites, I don't see that happening anytime soon.
It's kindof a mind-game though. A car's frame isn't that expensive to produce, even with a high-strength, lightweight composite. The auto manufaturers are still selling cars in upwards of $25k in the masses. So if that kind of construction were offered for around the same pricetag, why wouldn't people buy it? It would be lighter, getting better mileage. It would be stronger, less likely to break or warp. But who am I to say that? I'm just a nuclear engineer who's seen these materials in practice, not an automaker CEO.

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plastic vs. steel
by wcoffey81 / June 21, 2007 3:13 AM PDT
In reply to: Plastic vs steel, etc.

you should change that to rust-resistant steel is being used. rust proof would either be in the stainless/titanium direction or toward aluminum. either direction brigs both pluses and negatives such as galvanic reaction

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rust resistant vs rustproof
by deboernk / June 21, 2007 8:07 AM PDT
In reply to: plastic vs. steel

You are probably right. But if the material lasts for 20 years or so with no real detrimental effects from rust or oxidation what is the practical difference to the consumer? None, I suspect.

I believe that newer technologies such as powder coating over an alloyed steel material would make the rust issue a non-factor for all practical purposes.

What I am getting at is don't just jump on plastic as the cure all for manufacturing automobiles. Steel will still be around for a long time IMHO.

How recyclable are the carbon fiber composites?
Just a question as I do not know the answer to that one.

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rustproof
by wcoffey81 / June 21, 2007 11:43 PM PDT

they are making huge steps in the right direction and some of the products you mention are in use today. the only problem they have a hard time correcting is where two different metal types have to meet/join. some of the galvanic reactions are hard to imagine. remember all of the GM bumpers, in the 80's that fell off. that was from am aluminum bumper reinforcement meeting the steel bumper shock. they even had a thin plastic film in-between to keep them from touching

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An engineer's view
by AnotherEngineer / June 6, 2007 2:21 PM PDT

Cars have to become more fuel efficient. This can be addressed by improving engine efficiency (so they use less fuel) and/or by decreasing the weight of the car. Plastic and carbon-fiver panels are a given. You won't have a choice in the future.

Steel is easy for our auto makers to manipulate, but they will quickley learn to make carbon-fiber and fiberglass panels and strength members with the same efficiency.

They will also learn to build more efficient engines - electric and alternate fuel as well as gasoline powered. It's a new world and we are motivated. The bread line is not that far away!

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Unrecyclable
by mwooge / June 6, 2007 3:53 PM PDT

The main problem I see with plastic and composite car parts is that they can't be recycled. When the car goes bad, it'll be a big, bulky chunk of stuff to landfill.

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are you high?
by dstefani1970 / June 20, 2007 2:06 PM PDT
In reply to: Unrecyclable

you don't think plastic is unrecyclable? smoke another one dude

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Plastic or Metal....Protection
by Shirley97128 / June 6, 2007 6:17 PM PDT

Due to a recent accident, a guy was going about 50mph in a residential area and ran the stop sign, I was going 20mph and was in his way. The only thing that saved my life was the strudy build of my GMC Van and the Angel watching over me. I had been considering a smaller car for better gas mileage. Not any more.
Beaten & Broken, but alive,
Shirley

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(NT) Qualtiy, Not Material...
by alexanderpas / June 7, 2007 10:08 AM PDT
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But it is the material!!
by Andy77e / June 9, 2007 4:57 AM PDT

Come on people! What are ya thinking?!

You want to tell me it isn't plastic verses metal, that somehow "it's the quality" that makes a difference? Bull! I roll around in an 82 Buick Riviera. It's a small civilian legal tank.

I've been hit twice. Both times there was substancial damage to the other car, both times I didn't even have a scratch. One was a Honda Civic. He hit me so hard, that the whole front end of his car was bashed in like a bull dogs face. Not a scratch! Nothing! My chrome bumper had nothing on it to even indicated it had ever been hit!

How in the WORLD do you think plastic is safer than metal?! That's JOKE!

Three years ago there was a story about a guy in an large SUV, suburban I think. It rolled off a 30 foot drop, landed upside down. Guy climbed out and walked home. You think you'd survive that in a plastic car? Not a snowballs chance in hell, sorry!

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ROLL CAGE
by edge_bit / June 20, 2007 2:24 PM PDT

Um, I have a feeling plastic cars would be sturdier because they would have full roll cages rather than just a unibody eggshell protecting the passengers.

In an accident, high end unibody cars don't crush in the passenger compartment even a tiny bit.

Low-end unibody cars crush the passenger compartemnt all over.

Even a cheap plastic car with an industry standard roll cage will probably save your *** better than a tin-can unibody.

Sure, it's not the same as an SUV. It will likely be just about as good if not better, though.

Say you roll on the roof. Okay, you have half the curb weight resting on twice as strong of a roof. Remember these are not the plastics your kids play with but real, thick, high-quality plastics.

Anyway... I think most people see this idea and think of it as rolling around town in their kids' "Power Wheels".

NO! Not even close...

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Plastic versus Steel
by LeeWilliams / June 20, 2007 4:18 PM PDT
In reply to: ROLL CAGE

Some years ago when Corvettes were made with plastic I had a friend lose his life in an accident, because the car literally exploded when rolling and wound up i lots of small pieces. Since then I have had serious doubts about plastic. Also, recently saw a small Honda accord or Del Sol (cant remember which) that got hit by a 10 yr older 1/2 ton pickup and it was destroyed as well, with minor damage to the truck. Just a couple of incidents, but if this is good engineering..... I hate to see everything go to plastic.

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Corvettes are not plastic
by MudSnow / June 21, 2007 12:47 AM PDT
In reply to: Plastic versus Steel

Corvettes have never been made out of plastic. They are made out of fiberglass, which is a totally different thing. Plastic is flexible, not brittle.

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Both correct
by carolina1 / June 21, 2007 1:17 AM PDT

Fiberglass is only the reinforcing for the resin used. The resins used although not technically a plastic are in all practical terms from the same family and created by similar methods.
All plastics used in cars are filled to some extent to strengthen the material. Fiberglass strands are just one option over other fillers.

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fiberglass
by wcoffey81 / June 21, 2007 3:36 AM PDT
In reply to: Both correct

up until the late 70's the vette was still a fiberglass product. which is a polyester based resin reinforced with spun glass fibers. when the bodies changed in early 80's the went to a product called SMC (sheet moulded compound). new replacement panels for the older models are now made out of smc.
smc was really cool! it looked like a packed down furnace filter with an oily feel because of the resin which was already in it. the only size limit they had was because of the width of the mill used to produce the raw product. instead of adding a hardner to the resin, like in all polyester based systems, what was in SMC could be heat cured. one is exothermic and the other endothermic, in other words one produced heat during the cure and the other required the application of heat to cure. under heat and pressure they could form just about anything and the dies hardly ever needed maintainance unlike the dies used to stamp steel panels.

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Vettes have fiberglass bodies
by stevenhs / June 22, 2007 3:08 PM PDT
In reply to: fiberglass

Corvettes still have fiberglass bodies and always have since the beginning. There is not a year that they did not.

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fiberglass??
by wcoffey81 / June 23, 2007 5:04 AM PDT

if you are correct, why did GM send me to the tech center to be trained and certified in repairing the Corvette SMC panels???? starting with the body change in,i think, 1986 ALL CORVETTES WERE MADE WITH SMC PANELS!! all NOS panels for older models were also shifted to SMC. i still have my training manuals and certificates from all of my training at the GM tech center in Warren Mi. and Cleveland Oh. so unless you have some top-secret memo that they forgot to give me.......
take a sander to it, go down the the bare SMC and wipe it with a damp rag. it will be dark grey with a swirly pattern to it = SMC.
a brownish/grey color and you can see the full pattern of the fibers = polyester based fiberglass.
steven, i know these forums are a good to express ourselves but you shouldn't make blanket statements like you did. i could teach you a lot but you are going about it the wrong way. ask me how i know something or ask me if i'm positive about it but don't call me a liar!

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fiberglass2
by wcoffey81 / June 24, 2007 11:59 PM PDT
In reply to: fiberglass??

folks i am sorry! i let a troll get to me and i reacted poorly

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Try Google before posting
by make_or_break / June 26, 2007 8:07 AM PDT

Fiberglas-bodied Vettes have been consigned as a thing of the past (thankfully) with the last three generations of Corvettes.

As for plastics: as the technology stands now, I'll personally stay away from them in any of my future cars, particularly in the areas subjected to structural and severe impact loads. I recall some very vivid and catastrophic accidents in F1 where certain teams switched from titanium and other aluminum alloy structural members to carbon fiber and/or Kevlar. Accidents that invariably happened in the course of racing that occurred after the change were much more dramatic and injurious to the drivers.

The current state of technology with polymer-type structural members just isn't up to the toughness of metals; polymer-based materials more often than not literally shatter and explode upon impact rather than deform and absorb the collision energy like metals do. The same likely goes for long-term fatigue of materials as well. Moreover, subject polymers to engine and exhaust heat and environmental exposure such as UV...sure recipe for degradation and failure.

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by make_or_break - 26/06/07 15:07
by searcher-alpha / June 26, 2007 8:51 AM PDT

The comments you make about F1 cars construction being inferior to metal based monocoque chassis is flawed a recent coming togethor of a f1 car and the concrete walls of montreal at a speed of 160 mph resulted in a sprained ankle for the driver. Not quite the horrific result you normally get with a steel car hitting anything at that type of speed. Plastics are the future and most plastic panels can be recycled. In fact it is a requirement of most enlightened european goverments that most of the materials in new vehicles are recycleable including plastics they are lighter faster better handling and have to meet high safety standards.

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