What are the pros and cons of plastic cars?

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.

Kubica also suffered a concussion, which did keep him out of the U.S. GP the following week.

Yes you are correct in pointing this accident out. Kubica survived relatively unscathed considering the intensity of the crash. And the composite nose at the front of car's monocoque at the front of the car did have a lot to do with it, at least with the mild injuries to his feet and legs. However, as several F1 engineers and drivers have noted since the crash, the most likely reason Kubica lived through the massive deceleration that the CF structure imposed on his body was due to the HANS device that supported his neck and head.

I readily admit CF is used A LOT by F1 now, and the state of the technology today is vastly superior to the way composites were used in the 1990s. The performance of the material in this crash shows just how good composite implementations and structural designs has come since its early days (Ayrton Senna's fateful crash at San Marino, for instance, which is what I was referring to when I initially made that statement deriding composites. Obviously, a lot of engineering has finally gone into the methodology that I've been oblivious to). The relatively minor injuries that Kubica suffered shows that CF--when properly implemented--does work, and I'm properly corrected.

Yet that said, with Kubica's BMW the composite crush zone alone at the front of the car disintegrating on impact before the wall hit the rigid part of the monocoque probably would not have dissipated enough energy to have saved his life by itself given the speed at which the car was traveling at the time. The HANS device is likely the real reason he why lived. The car's structure just spared his legs and feet from the sort of nasty injuries the old style metal structure would've incurred while dissipating the crash deceleration in those days before composites, or the HANS device.

Modern Vettes use materials that are would qualify as plastics. The old fiberglass days are long past; ironically, in that earlier era those Corvettes used steel subframes to go with their fiberglass bodies. Nowadays Chevy has moved away from a totally steel chassis and used composite construction using generous amounts of aluminum (ironic, considering their tone vs Fords in their pickup truck ads), hydroformed polymers, titanium and even carbon fiber (which in a sense is an outgrowth of the original fiberglass).

Their structures are indeed tough; they are REQUIRED to be in order to get on the road. The car MUST meet all of the current safety regs in the U.S. and Europe. Hard to imagine a newer C5 to C7 Vette splintering to bits any worse that a comparable, mostly metal sports car would in a high speed accident, not that many of the latter actually exist these days with current manufacturing trends. Composites rule the automotive bleeding edges these days, especially with those makers who are keen to shed as much mass and improve mileage as humanly possible.

Now in the case of an EARLIER Vette (particularly in the C1 to C3 eras)...well, those cars are entirely different creatures when it came to structural crash integrity.

If two vehicles impact one another in a head on collision the vehicle with the greater mass/density will always sustain far less damage. Plastic is simply not as dense and heavy as steel. Plastic/composite vehicles would certainly be safer if (and its a big if!) all vehicles on the road were made of similar materials and their bumper heights, overall mass/densities were the same. From a physics perspective the vehicle requires material, be it metal, plastic or composite to absorb and distribute the force of an impact. Many modern vehicles are designed with crumple zones the purpose of which is to absorb the primary force of an impact. However, even a larger massed vehicle such as a truck can sustain catastrophic damage if it hits another vehicle or truck with a significant density at an off center impact. I have seen accident reonstructions involving truck drivers who were killed when their cabs crumpled after they struck other (even smaller trucks or vehicles) vehicles in the rear but off to one side of their front bumper. In those cases the force of the impact was directed entirely into the drivers side of the cab causing it to crumple and crush the driver. The point of this long post is simply to state that your probably better of with a metal material but that vehicle mass/speed and height/off-center points of impact may offset any material benefits.

Your post elegantly stated what I wanted to say. I will just add, I was in a "minor" accident when I was rear ended by a F-250 pickup truck in my Honda Odyssey van. The truck was going 20-30 mph and caused some damage to my rear door and bumper and huge damage to my body. I do not know the physics but I would never buy a plastic car because of all the heavier cars out there. I have had a 2.5 years of unremitting pain. I don't care how green you are or how much fuel you save, if you care about yourself and/or your family you will buy the heaviest car your conscience will allow.

Material density has nothing to do with crash damage.

It is true that the heavier vehicle (more mass) will absorb less energy in the crash, but it is the mass not the density. This why a heavy SUV or truck is "inherently" safer in a accident with a smaller vehicle. And why some people object to the crash testing into a solid barrier where the heavier vehicle is no longer favored.

Given a certain energy of impact, it is the strength of the material that determines amount of damage. You can have a dense material with little impact strength or a lightweight material with good impact strength. It is strength and not density that is important.

Also, damage to the vehicle and damage to the vehicle occupants are separate issues. Older cars often came out of accidents looking relatively unscathed, while all the occupants were killed. Now it is often the opposite case. You see accidents where you wonder how anyone could survive and then hear that the occupants received only minor injuries. To save passengers you want to absorb the energy. Absorbing energy most often means sacrificing the vehicle.

there are a huge number of factors in disecting collision damage. most people don't think about it though. what if a roadway is solid ice like we have here in Michigan sometimes, fresh slick tar or what if the same accident happened in Florida on one of the old coral/concrete road surfaces?? it changes everything!!

You are both correct. A higher density generally increases the overall toughness of a material. The form of its crystalline structure also affects the toughness. But, regardless of material, the biggest difference in any kind of collision is difference between mass. Another is angle of impact.

If two opposing objects collide with a relative difference in speed, one will transfer energy to another. The closer the mass between the two, the more energy is transferred. If you roll a bowling ball at another bowling ball of the same mass, all the energy is transferred if the impact is direct with no angle. The first bowling ball will stop and the ball that was struck will begin moving at the same speed you sent the first one. But when that bowling ball hits a pin, for example, the bowling ball will keep moving even though it moved the pin. That's because the difference between masses does not allow for a complete transfer on inertia.

When you apply that theory to cars, it makes sense. The worst case scenario for any car is to have a head on collision with another car of equal or greater mass. The other car will absorb all of your car's energy and transfer it's opposing inertia to yours. If it's heavier, you will move backwards after the impact.

But as the other person who replied to your post said, there are many other factors that go into car safety. Some include difference between heights of frame and chassis, or design of crumple zones, the angle of impact, and so on.

But take that data into the subject of this forum. The term "plastic car" does not mean plastic frame. It means that where heaveier metals would be used for things like door siding, the hood, the trunk, etc., the manufacturer would use lightweight plastics. Keep in mind that the current siding on any car, metal, fiberglass, or other composite, provides no protection in an impact. The frame, engine, and crumple zones do all the energy absorbtion.

The only reduction that the plastics would accomplish is reduction in weight. Therefore, increasing fuel efficiency. It would have nothing to do with safety because the siding on all cars currently being produced only keep the weather out. But plastics are easier to cut through than metal. It would become easier to remove somebody who is trapped in the car. Most of the siding would crack or pop off in a major impact, leaving the rescue crews with less metal to deal with when somebody is stuck in their car.

I hope this sheds some light on the subject. Most people in this forum that are against 'plastic cars' think that their metal siding somehow protects them. That's simply not true. I do believe that the frames could be replaced with a lightweight composite. But it would be stupid, for safety's sake, to replace critical frame portions with plastic.

As far as the SUV and 'old tank' theories go. Most cars on the road now are smaller and lighter. The only person that the tanks are safe for are the drivers and passengers of those vehicles. They are a danger to everyone else. The only reason they are safe for the occupants is because they obliterate the smaller cars that they will, inevitably, run into. People in SUVs, in general, have a false sense of security and pay less attention to the road. Typically, they also have the attitude of 'get outta my way', thinking that they own the road. That reminds me of a schoolyard bully, not a sophisticated, upper class citizen. A certain advertisement comes to mind. It was a poster showing a hummer. It had a picture of a particularly intimidating hum-v and stated "ALWAYS HAVE THE RIGHT OF WAY". That sickens me.

Being in the New London area, we see this all the time. The people here think that if your vehicle is more expensive/bigger than another, you have the right of way. They completely ignore all common sense as well as traffic laws. I can't wait until I get medically retired from the Navy so I can move away from this God-forsaken place.

When your talking physics, you are great. However, you make bold broad judgments on everyone else. As someone who claimed to believe in God, I wager he's not into this judgmental-ism. I personally am not into it either.

"People in SUVs, in general, have a false sense of security and pay less attention to the road. Typically, they also have the attitude of 'get outta my way', thinking that they own the road."

This is wrong for you to make that judgment, and wrong to slander others whom you have never met, even if, and to me that's a big if, you have any reason for doing so.

Having driven an SUV, that did not describe me. And even now in my 82 Buick, which pretty much is an urban tank, I am a safe drive. If anything drives me nutz, it's the high school kids in little Civic who think that because their car is only 80 inches long, means they can squeeze between me and the car in front of me, on the off ramp at 50 mph. Or floor it out of my Condo parking lot where dozens of children play. I don't see SUVs doing this. I see TOYotas, Hondas and Saturns doing this.

Or one of my favorite pet peeves is that seemingly useless lever just behind the steering wheel. I for some reason had thought it was too allow lights on my vehicle to denote to other drivers, my future intention of direction. Not to jerk the car over and have the light blink once *after* it was already 3/4 of the way into the other lane. Or some

And I also thought the (one) purpose of hazard lights was to warn people behind you, that traffic in front of you was slowed or stopped. Of course they just slam the brakes 1 car length from stopped traffic. (thankfully I make a point to *not* be behind a plastic midget mobile)

Finely speed limits. I like to use that nifty 80s cruise control at the speed limit. They like to floor it so their fart tin can muffler sounds like a lawn mower on steroids. They fly past on their 4-cylinder Lawnboy, while I cruise at 65. Now which one of us is a danger? Not me brother.

Now I want to make this clear, I'm not saying you didn't see an unsafe SUV driver. Bad drivers are everywhere. My personal favorite was an old lady at a store with a 90s Cadillac. In the full 15 minutes that was required for her to pull that car out of the parking space, she successfully hit 3 cars, the one in the row behind her car, and the two cars on either side of hers. Plastic does take minor hits better than metal, but in this case, it didn't help.

My point here is this. You are prejudice. You have a pre-judgement against SUV owners before you even know them simply because you don't like SUV. That's wrong.

First off, we've had similar discussions before. This time you made me laugh.
"I like to use that nifty 80s cruise control at the speed limit. They like to floor it so their fart tin can muffler sounds like a lawn mower on steroids"
I think the same thing. I chose not to get the 'convenience package'. I wouldn't mind having electric door locks, but I don't use the cruise control and all the other fancy electronic crap. You already know my father is a truck driver, so I grew up hearing horror stories about that kind of stuff going wrong. (i.e. cruise control on and the driver falling asleep)

Yes, I'm a little prejudice. It's not through anything but observation. I RARELY drive over the speed limit. Those little fart cars(bumble bees trapped in a tuna can) piss me off too. But being in my medical situation, I have to drive for fairly long distances to see neurosurgeons quite frequently. When I drive, I end up getting tail-gaited a lot, especially during the rush hours. I really don't mind it so much, to a point. I just slow down a few MPH. I get the best gas mileage between 60-65mph anyway. But if I'm in a lane where I can move after I've slowed, I let them pass for the most part. It's an easy, safe way of getting out of a potentially dangerous situation.

But what I have observed is exactly what I said.

In no way did I intend to say that everybody who drives an SUV is a jerk and everybody who drives a car is safe. I've had my fair share of run-ins with cars too.

I think of it like this. SUVs cost more than little cars. New Englanders(no, not all of them, but the ones you notice) tend to define themselves by the amount of money they have. This attitude doesn't just stop at being self-important. It spills over into their driving habits. I'm not trying to say that all people around here are like that, but it's my personal observation through social and driving experiences that many are.

I see a lot more cars than SUVs on the road. But the number of SUVs that tailgait, cut people off, refuse to use their turn signals, etc., is actually greater than the number of cars doing the same things. It's just a matter of observation on my part. In this area, there's a Navy base, pfeizer plants and offices, EB, and various other large industrial facilities. This brings a lot of money to the area. So I get the privelage of having to share the road with a lot of people who can afford to get 11mpg in that escalade.

The reason I make broad statements is because I have observed them. I see drivers as statistics. I don't intend for that to be interpreted as anything but an observation. I don't think it would make sense to make a statement after every paragraph stating that not everybody is that way. I think that sayint",in general" should show that I know there are exceptions and my personal opinion doesn't apply to everyone.

You made the reference to God. I know what you're saying. I am not passing judgement to anybody. I don't hate anybody just because they own an SUV. I am definitely not telling anybody they're going to hell or that they're a bad person. That would be judging them.

I used you as an example in a post because of the phrase "legal urban civillian tank" and nothing more. I gathered that you are a safe driver. But you're not the only one with that mentality. Driving a large vehicle gives you a false sense of security. When combined with the inconsiderate 'better than thou' mentality, it's a dangerous thing.

I apologize if you thought I was wagging my finger at you. I was not. I simply used your words to make an example.

While new england has its ups and downs for driving, I was stationed in SC for nearly 2 years. The drivers there seemed to act in a similar manner. They were just worse drivers as a whole. Even the most aggressive driver from up here would get run off the road in Charleston, SC. But that's just an observation of mine, and that's part of the reason I'm so laid back when driving up here. I feel the need to watch other drivers' habits to determine how safe I am when near them.

The paragraph about the old lady in the caddy was amusing too. I've seen similar things, but I've never heard it said quite so elegantly before. Truly, thanks for the laugh.

If in your tanks you kill the driver of the other vehicle do you care dont read like in these postings but if your car crumbled and takes the shock and both drivers and passengers are alive that a good outcome..

No ethical person person drives aggressively with a car, whether heavy or lightweight. But we all have seen such drivers on the road. Buying a sensible vehicle for your family is the same as buying insurance: it is the only factor we can control on the road except for driving with care ourselves. I had driven for almost 40 years without an accident, when a careless truck driver rear-ended me. I have a "permanent and stable" partial disability from a minor car accident. I am glad that the driver of the truck was not hurt, but I walked away injured for the rest of my life since my car was so much lighter than the truck that hit me.

all new vehicles have to meet minimum crash standards. that is why the very efficient VW "beetle" is not allowed to be imported into the US. yes, the poor little beetle designed in the late 40's or early 50's was still being built in Brazil, at least up until a few years ago. it doesn't meet front and rear crash standards so we can't have them here. we demand safer and safer and overlook the fact that someone has to pay for it.
for a collision to get into the greenhouse area of a modern car takes a pretty good hit

You assume they would have a full roll cage? Why? Site an example.

First off, a tin-can unibody isn't what I advocate. I advocate strong unibodies, like my 82 Buick. Having been hit twice, I can say I'm safer in it than any modern el-cheapo tiny car.

Second, a full roll cage would require enough steel to defeat the purpose of making it plastic.

Third, a full roll cage is expensive, just as making the car out of plastic is expensive. People are cheap. Cost cutting to satisfy people who don't want to pay for a good car, is exactly why they use paper thin sheet metal now.

Until I see a plastic car with a roll cage that is sturdy and cheap enough to buy, I still bet against plastic.

unless you are driving an 82 Buick X or J car what you have is not a unibody

I agree with you about heavy-duty steel, however, there is cheap plastic; hard plastic; and rubber-type plastics. If you're thinking of the sort that baby rattles are made of for making cars then I doubt they'd even get off the assembly line before the safety experts would condemn them.

There is a type of "plastic" that's called plastic only because it's man-made. It can be bashed a hundred times and never show a dent or fracture. Some Rrubber-Made products are similar to it. though it's a much thinner type than would be used for cars. I believe Saturn has been using it for several years with good results. A friend who has one of the older Saturn models said she got hit hard on the driver's side door which dented at contact, and then popped out. I saw the door and there wasn't a mark on it. She wasn't seriously hurt, but being softer than steel, if it hit against her body, I would think any injury would be less serious than hard steel ramming into her.

anyone ever heard of crumple zones? those suv's are the problem here, not the little cars that "explode" so if you don't have a scratch, and they don't have a scratch, where did the force go between the two 30 mph cars? it doesn't just jump into another dimention. you, the driver, are the scrambled egg inside. about being crushed, listen when these guys talk about roll cages. it has never been made of plastics and never will be. all i can see in the future is a turn to carbon based metals, but if you're worried about your gas guzzlin' suz getting a little dent after you kill the economic driver in the civic (which i happen to drive) you have bigger problems than metals versus plastics

I drive an 82 Buick. (urban street legal civilian tank) You drive an el-cheapo death-trap on wheels. I made my choice, I'm going to live. You make yours, and stop whining at others when you do.

Just because everyone doesn't choose to drive the same death trap you do, doesn't give you any right to complain.

Exactly. My volvo wagon door is so heavy that I have to drag it closed. My sister's Accord has doors that I slam shut because they are so light. I'll take my chances in the old volvo wagon any day.

i know the volvo falls into the tank catagory but it is a well respected tank. they have produced some vehicles that are an excellent cross between tank and daily driver, probably the first that marketed a car by it's safety record.

It's always comforting to indulge in oversimplification, because it doesn't require too much effort on the part of the "indulger". In this discussion, however, it seems a more circumspect way of looking at the topic at hand is called for. There are plastics, and there are plastics...there are metals and there are metals. To some, plastic has a connotation of fragility, and metal has a connotation of strength. However, if all the comments made in this forum by those who extol the virtues of plastic are moot, as the owner of the "small civilian legal tank" would have us believe, then how does he explain the fact that a vest made out of plastic can stop a bullet made out of metal traveling at a considerably higher velocity than the Honda Civic was when it crashed into his 85 Buick Riviera?

This is a fine point. But you are assuming that the plastics used a bullet proof vest would be the same used on a car. Can you make that point? No you can not. So the point is not relevant.

This is the same as saying a 25 foot thick wall of plastic surrounding my house, can not be penetrated by a hummer at top speed. Great. But pointless.

You would have to make the car out of plastic, of similar thickness and strength, in order to be as safe as a metal car. I would wager, and you can disagree, that a plastic car will not be built as strong nor as safe. If you can sight an example, then I'll change my opinion. If not, then this is a waste of time.

Alloy double deck bus roofs get dented and torn by trees moreso on wet days when they hang lower with the weight of the water but a fibreglass one seldom ever get more than a scratch..

Is fiberglass stronger than plastic? (I really don't know much about fiberglass) I know it's more expensive though. You think a car made from fiberglass (not a sports car) would be cheap enough to sell?

I question that...
It would be lighter though, that's a plus for fuel mileage.

In 1994, I hit a semi with my -67 Volvo Amazon.
The Amazon is pretty much built like most american cars of the same age.
It's basically a 50's construction.
I'm now injured for life.
I now drive a -01 Skoda Octavia Combi.
I bought it new, 6 years ago.
If I should have the same accident today, not a hair would be disturbed.
I would be able to walk away from it, without a mark on my body.

My new car is designed to absorb and distract the energy.
My old car was more like a truck, I absorbed all of the energy.

Ludicrous. Having seen similar wagons get in tangles with semis, where the driver was killed, the idea that "not a hair would be disturbed" is the most absurd thing I've heard yet on this forum.

But hey, keep your false sense of security.

Yes, if you hit a plastic car with a metal tank and the tank will win.
Your argument assumes that you are the only person driving a plastic car in a world where all other cars are tanks,,,of course that would be crazy! Think about the bigger picture,,,," what if everybody had plastic cars?" then both cars would share the impact.
Your whole "my car is safer" attitude is only thinking about your own safety,,,,ok,,,so when the day comes (and i hope it does not of course) that you hit somebody else in your tank, your own comments will be used against you. If you were not driving a tank then the other driver may have lived! Your car is safe for you, but perhaps a danger to others?

Simple replace all the dino age vehicles driving on conastoga wagon technology and replace with plastic. Then there won't be the question of Metal versus plastic.

We don't drive cars with 100lb front bumpers anymore because those wonderful things called crush zones and reinforced driver compartments were created.

If (and I hope it does not either) that day comes where some idiot in a midget mobile slams into my car, and they get hurt, it's their fault. I am in control of only myself and how I choose to be safe. It's not my fault they choose a plastic midget mobile.

It's a false assumption to assume they would live if I also had been driving a less safe car. Sorry I'm not going to buy your totalitarian belief system.