[vishy76]

Hi bhpians,

Let me just start off by saying that I do not have any personal grudges against any owner/car brand. This is just a poll based on your opinion.

Weight, the magical word that comes to your mind when you know you can't extract more out of your remapped engine or you want more fuel efficiency.

However, the word weight has become ever so important in the Indian automotive scene due to the increased demand for fuel efficient cars and more importantly, because manufacturers know that only 2 or 3 out of 10 customers would care about how heavy the body shell of their car is.

If I might put it this way, the equation for manufacturers 10 years back was:

More sheet metal = premium image = better sales

However, the equation now seems to have changed all of a sudden:

Less sheet metal = Fuel efficiency = Better sales

I will give you a classic example of this weight saving strategy now;

Volkswagen Jetta



The car is based on the old PQ-35 platform. This platform was conceived a decade back. The Jetta has a weight of around about 1.5 tons or 1450 Kg to be precise. Let's take another example now, shall we?

Skoda Octavia



The Octavia is based on the VAG group's MQB platform. Simply put, it is actually the successor of the Jetta when it comes to the platforms that these cars are based on.

The Octavia is around 100 Kg lighter than it's predecessor and the Jetta too.

And here comes the million dollar question. Some say that it is an advantage for the Octavia and helps power to weight ratio, however some say that the build of the Octy has been compromised and it feels lighter than the Laura or Jetta, both of which feel proper tanks.

It's not only true in the VAG group case. There have been similar observation with the older figo and the newer one, with the latter lacking the sheer build that the former had.

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

[mayankk]

Originally Posted by vishy76

Hi bhpians,

Let me just start off by saying that I do not have any personal grudges against any owner/car brand. This is just a poll based on your opinion.

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

How do you know all the weight reduction has been done by using thinner sheets? This sheet metal debate and thudifying theory has been done to death.
There is a crash test on youtube between a 50's behemoth and 2000's honda. The thin sheet metal car demolishes the giant.
So whether it is good or bad for the customer should be decided upon how the weight is being saved. Well built with good safety and power to weight and economy, better.

[arunphilip]

Oh, I wish it were that binary - being able to easily select good or bad.

I would prefer a car with lighter sheet metal for its better torque-to-weight ratio:

• If it could offer equivalent or better safety than a heavier car
• If it could offer comparable NVH to a heavier car (thicker sheet metal = lesser resonance)
• If it could offer comparable ride as a heavier car, i.e. a more planted feel

Now, none of these are exclusively an attribute of sheet metal thickness, there's other factors that come into play:

• Safety - is also a factor of how the car has been engineered (e.g. Honda's G-CON technology, Etios' very compelling crash-test scores)
• NVH - is also a factor of other components like beading, damping, glass thickness, etc. (e.g. Ambassadors won't score high here even though they have battleship-grade sheet metal)
• Planted ride - very dependent on suspension tuning

Given this complex relationship between many factors, I'd have to refrain from voting solely because the decision of a manufacturer to use lighter sheet metal doesn't mean steps have been taken to compensate for the loss of the tangential benefits of thicker sheet metal; and conversely, the presence of thicker sheet metal doesn't automatically confer these benefits.

[jetsetgo08]

A good debatable question. Wish there was a "can't say" option in the poll.

However, I would prefer thicker sheet metal to avoid unnecessary small dents on the panels caused by-
1) Tennis ball hits by the kids playing around.
2) Twigs of a tree landing on the car.
3) While washing the car.
4) Or in traffic, where the biker who lost balance leans on my car for support to prevent a fall. etc.

And many such irrelevant and silly situations where a thicker sheet metal helps without the compromise of FE & safety.

[Jaggu]

Lighter when the safety is not being compromised is ok, but what we have seen is the other way around in India. The panels of new gen cars are becoming like aluminum cans, getting dented at the slightest of impact, whole structure crumpling at heavier impact.

Efficiency, safety and practicality has to have a good balance. Till then i will trust the good ol armor more.

[SmartCat]

Almost every major "automotive trend" has been good for the customer. Anything that is "bad" for the customer will be rejected outright.

Similar threads:

http://www.team-bhp.com/forum/techni...es-matter.html
http://www.team-bhp.com/forum/indian...-vehicles.html

[sahibrain]

Originally Posted by arunphilip

Oh, I wish it were that binary - being able to easily select good or bad.

Originally Posted by jetsetgo08

However, I would prefer thicker sheet metal to avoid unnecessary small dents on the panels caused by-
1) Tennis ball hits by the kids playing around.
2) Twigs of a tree landing on the car.
3) While washing the car.
4) Or in traffic, where the biker who lost balance leans on my car for support to prevent a fall. etc.

And many such irrelevant and silly situations where a thicker sheet metal helps without the compromise of FE & safety.

I doubt (hope) that the current "light weight" models don't suffer from the above especially the points #2 and #3.


On the topic of weight reduction, i drive the Linea T-Jet (2012) model which weighs a lot to put it mildly. While the extra weight is not an issue for me, sometimes i do feel that there will surely be a scope to reduce the weight from some non-critical elements without compromising the structural integrity and driving dynamics. What mean is, the engine weights have reduced from the cast iron days to the aluminium days so weight loss in the car can indeed be a good thing. The F1 cars put in a lot of thought to reduce weight while not compromising the driver's safety, newer materials are introduced, etc. So if these are incrementally brought into production cars its a good thing.
To summarize, giving an analogy with the biological weight loss,
"As long as the weight loss is not a result of crash-diet (read quick fixes compromising safety) AND is obtained by building of muscles, increasing metabolism, etc (read well thought out and executed) it's good and definetly welcome !!"

[AYP]

Irrespective of the positives and negatives of having a thicker sheet metal car, I do like the 'thud' sound of the European cars. And it does sadden me to see the cars getting lighter. However, this change is bound to happen, just like the introduction of features like power steering(hydraulic) and now EPS. However, I do feel that even with the reduction of weight , the 'heavier' cars will continue to be heavier and will continue to give a 'thud' feeling.

The sad part is, the 'thud' effect will keep on reducing.

[k88k]

I voted 'Good'.

These days almost all the vehicle manufacturers are moving towards light-weighting and looks like the major driver is making cars more fuel efficient and emission friendly (mainly due to government's arm twisting). This is not restricted to four wheeler manufacturers alone. Commercial vehicles are also cutting down on use of sheet metal and going towards using composite materials, which are lighter in weight and don't compromise on strength as well.The answer to "Kitna deti hai?" still is a key buying factor for many Indians. Imagine, you get to own a hot hatch and you are also getting a dream mileage figure. You have the best of both the worlds!

Almost a decade back Maruti Suzuki had plans of reducing 1 gram of weight from every component of the car. I am pretty confident that if we compare the weight specs of the earlier generation MS cars to the refreshed ones, we will find differences.

Hyundai is also driving projects towards light-weighting their cars.

http://www.hindustantimes.com/busine...0U4F9Zi9H.html

Percentage of Sheet metal weight in car is a soft target it does have a significant cascading effect on mileage, efficiency and emissions. But, there is a limit to play around with sheet metal thickness as safety of the occupants can't be comprised. Manufacturers are now moving on to interior components like seats (e.g. Celerio thin seats), Parcel trays and Luggage boards.

[deerhunter]

Originally Posted by AYP

Irrespective of the positives and negatives of having a thicker sheet metal car, I do like the 'thud' sound of the European cars. And it does sadden me to see the cars getting lighter. However, this change is bound to happen, just like the introduction of features like power steering(hydraulic) and now EPS. However, I do feel that even with the reduction of weight , the 'heavier' cars will continue to be heavier and will continue to give a 'thud' feeling.

The sad part is, the 'thud' effect will keep on reducing.

The thud has got nothing to do with the weight of the car or even the sheet metal thickness. The thud that you hear is due to the door latch, dampers and the seal.

If Mercedes is to ever make a car with the thinnest outer sheet metal and lowest gross weight, they'll still make sure that the doors close with a thud.

Link

[abhishek46]

Originally Posted by mayankk

How do you know all the weight reduction has been done by using thinner sheets? This sheet metal debate and thudifying theory has been done to death.
There is a crash test on Youtube between a 50's behemoth and 2000's honda. The thin sheet metal car demolishes the giant.
So whether it is good or bad for the customer should be decided upon how the weight is being saved. Well built with good safety and power to weight and economy, better.

You have a good point there.
A lot of weight could be reduced from the structure itself, by clever engineering and high tensile materials.
Body panels are just one aspect of the weight reduction exercise.

Coming to crash safety, was the crash test you mention a head on collision between the 50's heavy weight & the 2000 honda?
I doubt the Honda will survive in this case.
Even more extreme example, sand/mining truck vs the safest of the cars. In case of head on collision, the car stands no chance.

Finally, even though manufacturers have proved that thin body panels can pass the crash tests due to clever structure inside, the real world is not a LAB. In real world the speed wont be precisely 64kmph/56kmph and the angle of impact & crash scenarios wont be fixed.

I would say that in real world crash scenario (which can happen from any direction, arbitrary speed), having both more mass along with clever engineering will hold an advantage.

[mayankk]

Originally Posted by abhishek46

.

I would say that in real world crash scenario (which can happen from any direction, arbitrary speed), having both more mass along with clever engineering will hold an advantage.

My bad. It was a Chevy Vs Chevy.

https://youtu.be/qQGfr6SvSIo

The big guy did not fare well

[for_cars1]

Originally Posted by vishy76

.......

However, the word weight has become ever so important in the Indian automotive scene due to the increased demand for fuel efficient cars and more importantly, because manufacturers know that only 2 or 3 out of 10 customers would care about how heavy the body shell of their car is.

.......

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

Originally Posted by AYP

The sad part is, the 'thud' effect will keep on reducing.

Originally Posted by deerhunter

.....
If Mercedes is to ever make a car with the thinnest outer sheet metal and lowest gross weight, they'll still make sure that the doors close with a thud.

Originally Posted by abhishek46

Finally, even though manufacturers have proved that thin body panels can pass the crash tests due to clever structure inside, the real world is not a LAB. In real world the speed wont be precisely 64kmph/56kmph and the angle of impact & crash scenarios wont be fixed.

I would say that in real world crash scenario (which can happen from any direction, arbitrary speed), having both more mass along with clever engineering will hold an advantage.

The statement that "Cars have been getting lighter generation by generation" is actually not true. There have been ups and downs in the weight of cars in general during the course of its evolution.

Digging into a bit of history for a better perspective

If one observes the general trend of the weight of automobiles during the course of the last century, they started out as heavy behemoths. The design philosophy was to make them as rigid (heavy sheet metal) as possible. These cars only gave a perception of being safe, the body/passenger cage would actually disintegrate and open up in a collision due to the absence of a passenger safety cage.
After the oil crisis in the 60s and 70s, cars started getting smaller and lighter to be more efficient and the trend continued through the 80s and most of the 90s and this is the period in which safety aspects of the design started to get a lot of attention with monocoque body, safety cage, crumple zones and focus on structural reinforcements, cars started getting heavier again after the late 90s.

The need to meet crash regulations especially in the EU and North American markets have actually dictated the weight of cars.
In addition to having a strong passenger safety cage, crumple zones and all the passive safety features, the cars designed for these markets have to have strong reinforcements, resistance to footwell intrusion, better side impact collision safety.

So cars designed for these markets end up becoming heavier just to meet the safety requirements, only then they become eligible to be sold/marketed. Even prospective buyers look at crash test results and make their purchasing decisions with more emphasis on safety aspects and select safer cars.

Even in these markets, the newer cars are coming out lighter than they use to be after using lighter composites and alloys such as Boron Steel. While they may be relatively lighter than before, they will still continue to be heavier compared to cars designed for emerging markets with weak regulations.
The Thud factor has mellowed down in the newer generation BMWs due to the use of lighter (yet strong) aluminium alloys on the doors


India is a relatively nascent car market where the Govt safety crash test regulations have been poor and customer mass awareness about safety (purchase decisions based on crash test results) is still yet to shape up.

In such a scenario, the manufacturer has a free hand in deciding how heavy or light the car can be. They are not bound to meet any high safety crash resistance standards like in the EU or NA, so they can get away by designing lighter cars for our market and cut the weight further to make them as fuel efficient as possible.
The popular purchasing decision is on fuel economy, the customer emphasis on structural safety is yet to catch up on a popular scale.

A car can be light yet safe with proper design. The sheet metal could be thin yet the passenger frame could be strong enough to resist intrusion with proper crumple zones to dissipate impact forces. But it would be good to have best of both worlds read: thicker sheet metal and strong safety cage/structure like the european design philosophy.

[GTO]

Cars are getting lighter & lighter because of three reasons:

- Meeting CAFE (Corporate Average Fuel Economy) requirements.

- Meeting ever stringent emission laws.

- Costs.

More metal alone won't make a car safer. However, all things being the same, a heavier car feels more solid. Just drive a Jetta & Octavia side by side and you'll know what I'm talking about. The old Jetta has an air of solidity that is missing in the new MQB Octavia.

Originally Posted by deerhunter

The thud has got nothing to do with the weight of the car or even the sheet metal thickness. The thud that you hear is due to the door latch, dampers and the seal.

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.

[Patriot_Vishwas]

I think it's very important to decrease weight. We need to ensure that we leave behind the only (known)habitable place in this galaxy for generations to come and increasing efficiency of our transportation is a ginormous positive step towards reducing our rate of destruction, of our own Earth.
A relevant example from the Indian Railways:

The light-weight aluminium coaches are made by Madrid-based manufacturer Talgo, which are capable of travelling at much higher speeds due to their weight and don’t need to de-accelerate at sharp turns compared to conventional coaches used by the Indian Railways.

If successful, the train is expected to cover the distance between Delhi and Mumbai within 12 hours, a journey that takes around 17 hours at present.

Besides being faster, the Talgo trains are also up to 30 per cent more energy efficient and environment friendly.

http://www.thehindu.com/news/nationa...le14482600.ece