[Jeroen]

I was actually taken a little aback with the title of this thread. That is not my impression at all. I guess it depends on how you look at this and in what time frame.

If you’d ask me I would have said that by and large cars are still getting heavier.

But then I started counting in the 1970-80s. Your average family saloon would weigh in at about 1000 kg, give or take 100 kilogram. My dad in those days had a DKW, VW1600, VW K70, Audi 80/100. Fast forward to the last decade and you will find that the average weight of cars in this segment has gone up with something like 300-500 kg at least.

The same is true for some of the cars I have owned. The first Fiesta we bought was just a little over 800 kg. Today’s Fiesta weighs in at approx 1100 kg. So a real porker!

Have a look:

https://www.carthrottle.com/post/10-...s-have-become/

So I would say this, cars getting lighter is a rather recent phenomena. And the “getting lighter” is not going as fast as the original “getting heavier” it seems! I don’t expect a family saloon weighing in under a tonnes any time soon!

Whether it’s a good or bad thing? Well, I don’t know. Because weight by itself doesn’t mean anything. At least not from a physical point of view. More weight is not necessarily more safe, more robust, more solid or anything like that. That is a huge misconception. Partially fuelled by some convenient examples that don’t take into consideration how physics work. Obviously, weight does have an impact on performance!

At an abstract level I would say weight is a resultant of a number of design, production and cost criteria. On most cars you could easily shave of say 100 kilogram by using high grade steels, different design/production techniques. Everything could remain the same, except the cost which could well be prohibitive!

So in order to come to some sort of qualitative type of statement regarding whether this is good or bad, we need to understand what else changes. Simply put. If everything stays the same and a car gets lighter, there is no gain. But if it gets more expensive, or comprises on safety it might not. So the question is, what value do we as owners/drivers get out of this less weight? Better performance, safety, or what?

Things in the real world are rarely as black and white as we would like them to be.

In quite a few countries, road tax could be based (partially) on curb weight, so even if everything else stays the same you might safe some bucks on road tax

Jeroen

[deerhunter]

Originally Posted by GTO

All good in theory, but not in the real world. My 2005 C220's door shut like a tijori. That of the new generations feels much lighter (dare I say Japanese) in comparison. It's a similar case with the E60 5-Series (solid) and my F10 5-Series (light aluminium doors). Cars are getting more & more equipment (emissions hardware, features etc.), but at the same time, manufacturers have to control their kerb weight. Something's got to give.

2005 C220 is lighter than the current one, isnt it? Still the lighter one has a better thud. Same with E60 and F10, but then this maybe due to lighter doors like you said.

[King_pin09]

My vote goes for "Bad"

Although thin metal sheets with properly designed and functional crumple Zones may protect the occupants during a crash of moderate intensity however in cases of high intensity crashes such as a speeding car involved in a head on collision with a speeding truck, I bet no one would be spared.

The game takes an entirely new dimension when the car is involved in low intensity crashes such as hitting a street dog or say a plastic barrel or say a just parked bicycle at 40-50 Km/hr speed, the collision surface would be scarily damaged and the car being rendered unfit for further journey until repaired. The risk of occupants being stranded in middle of nowhere cannot be ruled out. Why just limit to crashes alone just consider the case of a coconut fall or a jackfruit on the car roof; the protection of occupants would not be guaranteed in case of fragile cars such as a Maruti or a Honda (which themselves would turn unrecognizable in such eventualities), I would rather feel more secured in an Ambassador.

Considering the totality, it is essential that car makers develop a strong and safe car and not just make paper thin bodies and rely heavily on crumple zone theory for purported protection of the occupants and leaving the rest to the mercy of God. Of course there lies a hidden interest to make merry on repair bills later if the owner survives the crash.

At the end of the day, the Life of a human being is much more important than commercial interests.

[Superleggera]

I voted for good and the reason is we can achieve better fuel efficiency and reduced emissions by cutting down sheet metal weight and still not compromise on the safety aspects of the vehicle.
The classic example is Fords F150 pickup truck which moved to an all-Aluminum frame starting from current generation. This being Ford’s bread and butter model in USA, has a reputation of “Built Tough , Ford spent 6 years and $ 1B to the R&D. This is a big success, F150’s still enjoy the top positions in sale charts.
It was said to be Alan Mulally’s idea. – the ex CEO of Boeing (and Ford), who said if Airplanes can be built using Aluminum, Trucks can sure be !

[BLACKBLADE]

The automotive steel industry is continuously developing newer light weight steels, experimenting with newer alloying elements, which will increase the strength and formability, while keeping the weight as low as possible, to help auto-makers meet the ever increasing fuel economy standards and stringent emission norms.

What is heavy is not necessarily strong and vice versa. Also what is light and strong, definitely does not come cheaper, especially when it is to be made easily formable. Formability is very important for automotive steels, in order to achieve a variety of design intents in order to make that sleek and sexy looking car, which is aerodynamically efficient as well.

So steel makers are ever trying to develop lighter weight, high strength and easily formable steels while aiming to keep the costs lower. Improved Tensile strength and percentage elongation (a measure of ductility) are the key points for Automotive sheet metal industry.

Came across this video on the challenges for new generation automotive steel industry.

click on the link

Also found many interesting articles about futuristic technologies in automotive weight reduction in Green car congress

[wildsdi5530]

What I hate about thinner sheet metal is the dings that occur due to falling leaves. Someone puts a bag on your roof and it bends down. My labs tail has caused so many minor dents. Never had such issues in previous cars.

[dark.knight]

Originally Posted by vishy76

My question is, with cars getting lighter generation by generation, is it good or bad for customers in the long term?

When I saw the title, I went "oh, no", I hope you are aware that a thread with a similar title exists somewhere in the BHP archives where a severe battle took place between those who owned light cars and those who owned heavy cars. I guess we've all moved on since, with both the sides keeping distance with each other. However for the same purpose of educating the readers, I shall post what I know of the matter.

Yes, cars are getting lighter and that is not going to change, ever, it is the Holy Grail of car production. BMW's boast of going lighter with each passing generation as do many other luxury brands, but I'll use BMW as an example because a) its my favorite brand b) they understand weight cutting better than almost anyone.

How do they get it lighter?
- They use carbon fibre reinforced plastic and have increased the use of it progressively. To justify its use, carbon fibre low modulus has a tensile strength of 34.8 million psi, above normal steels 29 million psi and its ultra high modulus (more layers of carbon fibre weaving) has a tensile strength of 75 million-100+ million psi. This despite being lighter than steel.
- Use of aluminium in areas where resistance needs to be minimal yet rigid, this is why frontal beams are made of it (33% lighter than steel).
- Use of steel, high strength steel & ultra high strength steel in areas where they are required respectively, they use different grades so that affordability is kept in check.
- They make the front axle in aluminium to counterbalance the heavier steel rear axle (now also partly in aluminium) in the rear and to make the front half lighter to compensate for engine weight.

A mention must also be made of the only brand that makes its own steel and cars both (thus gaining the title of the most in-house leveraged car company on earth), Hyundai. They also make every grade of steel possible from regular to ultra-high strength steel (currently the strongest steel on earth for mobility solutions). Hyundai also hot-stamps its UHSS so that the process is more energy efficient and the final stamped part is stronger than ever, its more rigid than a cold-stamped part :

https://www.youtube.com/watch?v=73KCuNqZYHk

As far as the Indian scenario is concerned, we are at baby steps, to be frank we are not a developed country even remotely whatever else the blind patriots may have you believe. We as a society lack the sense and sensibilities, the legal system is not nearly all that it can be and consumer rights is next to zero (save for the nationwide once-a-month victory in a consumer court). Relying on sheet metal for keeping weight and costs in check is a very rudimentary, unscientific way of getting to the goal, one can say that the sheet needs to be firm and rigid to isolate noise (yes there is a difference in even the sound of rain on cars with different gauges with the thicker one being less noisy due to lower resonance), and also bear the brunt of small scrapes and bruises done by our ever-malevolent fellow motorists.

A sheet metal rigidity test is simple, just push, poke and press the panels and it'd be plenty evident and you can avoid it. However what's inside at the frame structure is a Rs.10 lakh question (see what I did there?) Lightness of cars done scientifically and with good intention is superb, I love the environment and if all the cars lose some weight, become more efficient, then all the better for earth.

Carbon di-oxide (CO2) emission both without ethanol :
19.64 pounds per gallon of petrol burnt
22.38 pounds per gallon of diesel burnt

Source https://www.eia.gov/tools/faqs/faq.cfm?id=307&t=11

Lets assume a weighted average of 20 between the two fuels, per one million gallons of fuel consumed there'd be 20 million pounds of CO2, released into the atmosphere, lets say the car companies manage to better the efficiency by 20% by cutting engine weight and body weight that's 4 million pounds of CO2 cut-down in this scenario. Makes sense when the figures are put to a world-scale where the benefits would be thousands of times more per annum.

For better quality, we must spend more.. there is no other option. Car companies exist to make sales and they'd love to sell us a better product at a higher price, but short of that since they're dealing with many hundreds of million $ expenses, they need to cut corners so that they can match our pricing expectations and achieve their sales. I leave it to the community to decide the rest.

[dailydriver]

Cars have consistently been shedding weight over the years. This has been necessitated because of changing norms/demands and, more often than not, is backed up and compensated by technical advancements that are rarely visible to the naked eye. Dings and dents notwithstanding, what matters is the overall integrity of the car. So, lean and mean is the way to go.

Originally Posted by wildsdi5530

What I hate about thinner sheet metal is the dings that occur due to falling leaves. Someone puts a bag on your roof and it bends down. My labs tail has caused so many minor dents. Never had such issues in previous cars.

Leaves causing dings and a dog's tail dents! Hope you are just joking. Which car are you referring to here?

[gkrishk]

Originally Posted by dark.knight

A mention must also be made of the only brand that makes its own steel and cars both (thus gaining the title of the most in-house leveraged car company on earth), Hyundai.

Don't Tatas make both steel and cars?

[wildsdi5530]

Originally Posted by dailydriver

Leaves causing dings and a dog's tail dents! Hope you are just joking. Which car are you referring to here?

Honda Mobilio. Not leaves exactly, but these red flowers with a brown husk sort of thing. And my dog is a heavy Labrador with a huge tail. But fact remains that similar dings are not caused in my 2004 Alto and 2008 NHC.

[H_Dogg72]

Originally Posted by wildsdi5530

What I hate about thinner sheet metal is the dings that occur due to falling leaves. Someone puts a bag on your roof and it bends down. My labs tail has caused so many minor dents. Never had such issues in previous cars.

Lolololol my Dalmation used to do the same, thankfully never got a dent on the Innova's panels

[shankar.balan]

Originally Posted by wildsdi5530

Honda Mobilio. Not leaves exactly, but these red flowers with a brown husk sort of thing. And my dog is a heavy Labrador with a huge tail. But fact remains that similar dings are not caused in my 2004 Alto and 2008 NHC.

Ha ha! Thumpy Tail Labby causing dents on a great big motor car!
Yes, indeed, I also kind of dislike the thin ness of these new cars sheet metal work. Cant even lean on a car fender these days without being worried that it will bend and go out of shape like a papadum!

[Aaron:)]

Voted for good.

The proverbial 'thud' or 'thunk' sound depends more on the door seal and dampers, as someone has already mentioned before, eg i20.

Lighter weight does not necessarily mean lower safety levels, eg Etios.

Excess weight hampers performance, fuel economy and emissions. eg Punto.

[wilful]

Not voting because of a number of imponderables.
A good balance of heft, safety etc would be my choice but where that balance lies is open to debate.
I can't however get over that sneaking suspicion in my mind that lighter and lighter may not be all that good.

[hillsnrains]

I have voted for good.

With the advancement of technology (read research), we should definitely reach equal or better strength/stiffness with less weight. Here are two primary reasons as I can think of
1. Advanced structural design/analysis
2. Development of new materials like high strength alloys, use of composites etc.

Saving weight is always good for the company, customer and earth (we have limited reserves of raw material, less pollution etc.) without compromising the safety and driving dynamics. Weight saving is one of the important criteria for all Automobile R&D across globe.