RE: Light cars are not the answer: Tell Me I'm Wrong
Discussion
Devil2575 said:
Those pictures aren't to scale though. Look at the difference in the numbers and it isn't anywhere near as the pictures suggest.
Regardless of the picture scale, they're still much bigger. Imagine putting 4cm spacers on each rear wheel of the E46, it would look outrageous, but that is how much wider the track is on the F30. It doesn't sound like much, but when parking in town or threading it down a B-road it makes a big difference.The industry does actually track the $ per kilo saved.
Karl-Friedrich Stracke, President Fahrzeugtechnik & Engineering of Magna Steyr : "In terms of what we see on the market this depends very much on the segment of vehicles. For example, mass produced segment A, B and C cars come with a per kg amount in the range of 2-5 Euro they generate for weight reduction, whereas a premium automaker may be willing to pay more."
https://www.just-auto.com/analysis/the-challenge-o...
(before the flaming begins, in the interests of openness, was written by one of my analysts)
Karl-Friedrich Stracke, President Fahrzeugtechnik & Engineering of Magna Steyr : "In terms of what we see on the market this depends very much on the segment of vehicles. For example, mass produced segment A, B and C cars come with a per kg amount in the range of 2-5 Euro they generate for weight reduction, whereas a premium automaker may be willing to pay more."
https://www.just-auto.com/analysis/the-challenge-o...
(before the flaming begins, in the interests of openness, was written by one of my analysts)
Devil2575 said:
bennyboysvuk said:
Regardless of the picture scale, they're still much bigger.
The F30 is 6 cm longer than the E46, so 3.4% longer.It's 1% higher and 4% wider.
I'm not sure i'd describe it as much bigger at all. Slightly bigger perhaps.
If you drew a box the size of each one, as you say there'd be little difference in the sizes of the boxes. However the proportion of those boxes that is filled with car has increased massively.
Park a 90s generation Mondeo next to a new one and the difference is extraordinary - how on Earth was the old one able to perform all the family tasks it did, surely we'd have been renting luton vans galore...
Sway said:
That's only in terms of it's extremities though isn't it?
If you drew a box the size of each one, as you say there'd be little difference in the sizes of the boxes. However the proportion of those boxes that is filled with car has increased massively.
Park a 90s generation Mondeo next to a new one and the difference is extraordinary - how on Earth was the old one able to perform all the family tasks it did, surely we'd have been renting luton vans galore...
The new Mondeo is massive though. I think the key with the 3 series is that the increase is size is more apparent E30 to F30. If you drew a box the size of each one, as you say there'd be little difference in the sizes of the boxes. However the proportion of those boxes that is filled with car has increased massively.
Park a 90s generation Mondeo next to a new one and the difference is extraordinary - how on Earth was the old one able to perform all the family tasks it did, surely we'd have been renting luton vans galore...
My parents had a Vauxhall Chevette and 5 of us used to get in it regularly and go on Holiday for two weeks at a time. The biggest car they every had was a Mk2 cavalier and we managed fine. Mind you child seats didn't exist then. You simply couldn't get three young kids in a car that size anymore.
Devil2575 said:
Sway said:
That's only in terms of it's extremities though isn't it?
If you drew a box the size of each one, as you say there'd be little difference in the sizes of the boxes. However the proportion of those boxes that is filled with car has increased massively.
Park a 90s generation Mondeo next to a new one and the difference is extraordinary - how on Earth was the old one able to perform all the family tasks it did, surely we'd have been renting luton vans galore...
The new Mondeo is massive though. I think the key with the 3 series is that the increase is size is more apparent E30 to F30. If you drew a box the size of each one, as you say there'd be little difference in the sizes of the boxes. However the proportion of those boxes that is filled with car has increased massively.
Park a 90s generation Mondeo next to a new one and the difference is extraordinary - how on Earth was the old one able to perform all the family tasks it did, surely we'd have been renting luton vans galore...
My parents had a Vauxhall Chevette and 5 of us used to get in it regularly and go on Holiday for two weeks at a time. The biggest car they every had was a Mk2 cavalier and we managed fine. Mind you child seats didn't exist then. You simply couldn't get three young kids in a car that size anymore.
But it is odd how people feel they need more space these days. We used to tour Europe in the Marina Estate with 2 adults 2 kids and an enormous frame tent, plus all the other camping paraphenalia
In response to the original article (which I've only just seen), I'm not sure that an excess of noise, vibration and harshness is purely down to a lack of weight, or even down to that at all. Most cars that obsessionally shave weight, such as the 4C and Elise mentioned in the article, are back to basics sports cars and lots of people like them to be raw. Personally, I'm no fan of noise in a car and like it at a minimum and I don't see a link between handling prowess and noise, but I don't think I'm typical. I'd happily drive an Elise with an extra 20kg of sound deadening, because I think it would enhance the car enough to excuse the slight increase in weight - most people don't think like that though.
Secondly, I see the conversation has moved to being about size and yes, modern cars are far bigger than cars were ten years ago, and ten years before that. Just look at the ridiculous progression at VW, where they've made a Golf size car since the late 70s, but because the Golf keeps getting bigger with each generation they keep having to introduce models underneath it: firstly the Polo, created as Golf sized when the Golf mk2 was produced bigger than the mk1, then the Lupo, then the Fox and now the Up! It's daft.
Secondly, I see the conversation has moved to being about size and yes, modern cars are far bigger than cars were ten years ago, and ten years before that. Just look at the ridiculous progression at VW, where they've made a Golf size car since the late 70s, but because the Golf keeps getting bigger with each generation they keep having to introduce models underneath it: firstly the Polo, created as Golf sized when the Golf mk2 was produced bigger than the mk1, then the Lupo, then the Fox and now the Up! It's daft.
If heavier cars make them handle better (and presumably go faster), then why dont f1 cars just keep adding weight and adding weight till they are optimally performing...?
Or if the aero is too much, then choose a category where cars arent planes in disguise. WRC then, where aero plays a much reduced role?
Or if the aero is too much, then choose a category where cars arent planes in disguise. WRC then, where aero plays a much reduced role?
One advantage of small light cars is that there is less room to fill them up with additional household, sports and other 'might be useful' rubbish. For example, I suspect that most families with large cars and small children drive around in vehicles that weigh rather more than their delivery specification.
There is middle ground, though not super light and not really an everyday driver my Noble M400 was astonishing in ride compliance and sheer grip.
One of the quickest most comfortable cars I have ever owned.
The penalty in the end was outright finish and reliability.
And of course no room for golf clubs or kids in the back!
One of the quickest most comfortable cars I have ever owned.
The penalty in the end was outright finish and reliability.
And of course no room for golf clubs or kids in the back!
big_rob_sydney said:
If heavier cars make them handle better (and presumably go faster), then why dont f1 cars just keep adding weight and adding weight till they are optimally performing...?
Or if the aero is too much, then choose a category where cars arent planes in disguise. WRC then, where aero plays a much reduced role?
Which aspect of handling are you referring to? I've searched back through the pages and can't find the post that you're replying to. Weight will always hurt performance, so whilst there may be some subtle areas where weight is a benefit, they will be massively over-shadowed by a heavier car's inability to brake and accelerate as quickly as a lighter one. Most of a racing lap is straights, during which you're either accelerating or braking, both of which are governed by Newton's second law. Aero of course increases the downward force on the tyres without increasing weight, thus it's amazing effectiveness. I wasn't sure about your second comment either regarding aero - what was that in response to?Or if the aero is too much, then choose a category where cars arent planes in disguise. WRC then, where aero plays a much reduced role?
For some balance, a 1.2 Peuegot 208; a pretty run of the mill hatchback with acceptable levels of NVH and quality etc has a book weight of 975kg.
I can't say if this is dry or wet but compare that to a 1.1 205 of the day and take into account that the 208 has A/C, more technology, is hugely safer and is physically bigger than a 205 at 780kg and that isn't too bad of an increase I don't think.
Fiesta's with similar sized engines these days are down to ~1000kg weights as well. Not sure about the rest of the competition.
I can't say if this is dry or wet but compare that to a 1.1 205 of the day and take into account that the 208 has A/C, more technology, is hugely safer and is physically bigger than a 205 at 780kg and that isn't too bad of an increase I don't think.
Fiesta's with similar sized engines these days are down to ~1000kg weights as well. Not sure about the rest of the competition.
I agree for the following two reasons:
1. A larger car is bigger in proportion to the sprung mass going up and down at the corners as the car rides. A bigger the sprung mass in comparison to the unsprung mass, the more the vehicle glides over the road surface imperfections.
2. Grip, tyre grip (mju) is dependent on two things: Weight acting down into the road, and the coefficient of friction of the tyre. Not tyre width. Wider tyres are beneficial for handling, and to give an acceptable tyre life with stickier compound tyres which wear out faster. So in this respect, in the absence of downforce, a heavier car will grip better.
1. A larger car is bigger in proportion to the sprung mass going up and down at the corners as the car rides. A bigger the sprung mass in comparison to the unsprung mass, the more the vehicle glides over the road surface imperfections.
2. Grip, tyre grip (mju) is dependent on two things: Weight acting down into the road, and the coefficient of friction of the tyre. Not tyre width. Wider tyres are beneficial for handling, and to give an acceptable tyre life with stickier compound tyres which wear out faster. So in this respect, in the absence of downforce, a heavier car will grip better.
goodo said:
... a heavier car will grip better.
...but needs that extra grip (and more as I was advised earlier in the thread) to turn due to its extra inertia. Net effect; lighter cars still have a cornering advantage just in terms of grip, let alone body roll etc.This reminds me of a recent spirited drive I was on in my 540kg car. Came up behind an Evo X who proceeded to give it the full beans round a roundabout (presumably because he saw me behind him). I would say he was a decent driver and certainly pushing hard as he understeered then oversteered slightly so was right on the edge of grip. Meanwhile I followed him round feeling like I could have been doing another 5 or 10 mph, despite having fairly mediocre tyres at the time and a poor geo setup.
I just thought it was quite interesting seeing the difference around a constant radius corner between a very capable but heavy car and a not-especially-good half tonne kitcar. Watching it gave you a real sense of the mass of the Evo tugging it away from the apex.
goodo said:
I agree for the following two reasons:
1. A larger car is bigger in proportion to the sprung mass going up and down at the corners as the car rides. A bigger the sprung mass in comparison to the unsprung mass, the more the vehicle glides over the road surface imperfections.
2. Grip, tyre grip (mju) is dependent on two things: Weight acting down into the road, and the coefficient of friction of the tyre. Not tyre width. Wider tyres are beneficial for handling, and to give an acceptable tyre life with stickier compound tyres which wear out faster. So in this respect, in the absence of downforce, a heavier car will grip better.
Point 1, correct, point 2, boll*cks i'm afraid!1. A larger car is bigger in proportion to the sprung mass going up and down at the corners as the car rides. A bigger the sprung mass in comparison to the unsprung mass, the more the vehicle glides over the road surface imperfections.
2. Grip, tyre grip (mju) is dependent on two things: Weight acting down into the road, and the coefficient of friction of the tyre. Not tyre width. Wider tyres are beneficial for handling, and to give an acceptable tyre life with stickier compound tyres which wear out faster. So in this respect, in the absence of downforce, a heavier car will grip better.
mU is a ratiometric unitless constant that is used to denote the co-efficient of friction between two objects. Tyre width DOES increase the maximum transferable force at the contact patch, because they are not just using Coulomb friction, in fact, tyres are like "velcro". The rubber of their surface forms, moulds and deforms around the macroscopic surface profile of the road, and this "mechanical" interlocking boosts static friction, meaning a tyre can generate a mU of more than 1. This is also why tyre mU decreases with both speed and slip, as there is simply less time for the rubber and road to interlock.
Now, yes, the normal load of a tyre increases the maximum force capability at the contact patch, but if that extra normal force comes from more mass, then it does NOT increase the cars maximum grip or traction, because the same amount of extra force is required to accelerate the extra mass! (F=MA, 1 = 1 x 1, and 10 = 10 x 1, A is still 1 in both cases)
This is why the maximum lateral or longitudinal accelerate for a car is set not by it's absolute mass or downforce, but by the ratio between them. In effect, downforce is "massless weight", it adds normal load to the tyres,but not mass that has to be accelerated.
So, a 1000kg car making 100kg, will gain 0.1G, but 1 100Kg car making the same 100kg downforce gains 1G! In extremis, say a Formula 1 car, the downforce is greater than the mass, resulting in the capability for massive accelerations!
RobM77 said:
You beat me to it 
The relationship between a tyre and Tarmac is not just a Mu*R relationship, as it would be for a hard object on a hard surface, like a rock sliding on Tarmac or a cupboard being pushed across the floor.It would be true if you had some additional mass to accelerate that didn't apply any normal force - something very heavy on the end of a tow rope...
otolith said:
RobM77 said:
You beat me to it The relationship between a tyre and Tarmac is not just a Mu*R relationship, as it would be for a hard object on a hard surface, like a rock sliding on Tarmac or a cupboard being pushed across the floor.It would be true if you had some additional mass to accelerate that didn't apply any normal force - something very heavy on the end of a tow rope...
The tyre/Tarmac interaction is quite complicated, but most other vehicle physics, such as why 10 tonne lorries don't corner ten times faster than 1 tonne cars, is thankfully quite straightforward. Can't remember where I read it, but a recent interview with one of the Porsche boffs (think it was Andreas Preuninger) when questioned about the "controversial" new GT3 (after he'd finally managed to get the journo off the subject of pdk and epas...yawn!) admitted that inevitably cars had got heavier as they had become more tech laden and to conform with crash legislation. His view was that despite this the driving dynamics were maintained or even improved by improvements in engine and chassis technology, and that lightness was still important for efficiency but it was no longer the holy grail of performance. This much has been proven by the latest and fastest GT3, the 918, GTR, Veyron etc. While the Veyron is obviously very heavy, which undoubtedly blunts it's track performance, it was never designed as a track car. And few that have been fortunate enough to experience it seem to have found it wanting...again,except perhaps the Stig.
I'm no lover of profligacy of the order of some of the bloated high performance machinery as we have seen over the years, and we all love a lightweight that responds like a gnat, but if you want to have daily use from it, sometimes a compromise is necessary, and should not always be detrimental.
I suppose if you compare two similarly equipped supercars: the 991 turbo s and the GTR, they are both similar in performance, power output and accommodation, while taking different approaches in terms of layout. What is surprising is how close they both are considering their weight difference. Maybe that benchmark is proof enough. And while the GTR appears to be the comparitive bargain, which the fans love to use to batter the 911 with, I suspect it makes Nissan less profit than the Turbo does for Porsche.
My main concern with the weight of modern cars is that a lot of the tech that ads weight is often there to increase the model's appeal ie optional extras or to satisfy health and safety/emissions legislation, much of which offsets the greater mechanical efficiency tech designed to make cars more frugal, not helped at all by the official fuel consumption test, which is about as trustworthy as a politician's expenses claim form.
I'm no lover of profligacy of the order of some of the bloated high performance machinery as we have seen over the years, and we all love a lightweight that responds like a gnat, but if you want to have daily use from it, sometimes a compromise is necessary, and should not always be detrimental.
I suppose if you compare two similarly equipped supercars: the 991 turbo s and the GTR, they are both similar in performance, power output and accommodation, while taking different approaches in terms of layout. What is surprising is how close they both are considering their weight difference. Maybe that benchmark is proof enough. And while the GTR appears to be the comparitive bargain, which the fans love to use to batter the 911 with, I suspect it makes Nissan less profit than the Turbo does for Porsche.
My main concern with the weight of modern cars is that a lot of the tech that ads weight is often there to increase the model's appeal ie optional extras or to satisfy health and safety/emissions legislation, much of which offsets the greater mechanical efficiency tech designed to make cars more frugal, not helped at all by the official fuel consumption test, which is about as trustworthy as a politician's expenses claim form.
Edited by shipoftheseus on Monday 26th January 04:37
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