Test Weights vs Kerb Weight

[DataHunter]

I'm really no expert on this, but aren't EU weights supposed to be taken with a vehicle that is believed to be representative of the most common options fitted to the car? I've had a quick scan of European Directive 95/48/EC which talks about the masses to be added, but I suspect the details of variation from type approval are buried within another docu...

That's a good point. Granted, there is no easy way to back-calculate the weight of options on a car without sourcing internal literature. Still, this is important information to consider.

"And for anyone who still suspects Maranello’s boys are employing dodgy tactics to secure favourable publicity, consider this. Shortly after we figured Ferrari’s own Speciale for our road test, we figured another.

The car was supplied by a reader. To tell you who owned it or why they’d risk souring their relationship with Ferrari by lending it to us would be a huge betrayal of confidence – so don’t ask.

But, despite being in less-than-perfect running order, the second Speciale replicated the performance of the first on maximum in-gear acceleration on every 20mph increment between 30- and 90mph in fourth gear to within a tenth of a second.

So there you have it. Ferrari isn’t afraid of track comparisons. Ferrari doesn’t supply bent press cars. And Ferrari certainly doesn’t need to send the cavalry along when we test their new models in future – because even when they don’t, we end up with near-enough identical results. End of."

Ferrari 458 Speciale versus McLaren 650S: what really happened | Autocar

Indeed. The weight and performance of Ferrari's cars are very consistent and reliable (just check out the 458's numbers in my original post, they are within one percent of each other!). I was curious, however, if you might have a scan of the LaFerrari's test by Quattroruote; the LaFerrari is a great car, and Quattroruote is a great magazine - putting the two together sounds like a test made in heaven.

 

[bmwz4coupe]

I'm really no expert on this, but aren't EU weights supposed to be taken with a vehicle that is believed to be representative of the most common options fitted to the car? I've had a quick scan of European Directive 95/48/EC which talks about the masses to be added, but I suspect the details of variation from type approval are buried within another docu...

No, EU weight (and also the anerican curb weight I belive) is the weight of the car without any options. Many of the options will increase the weight of the car, like electric seats and sun roof. And some options will actually reduce the weight, like lightweight sportseat, rims or other carbon pieces.

 

[bmwz4coupe]

The issue of weight often crops up in discussions about cars, and I think there's a lack of understanding which often leads to poor comparison*. All too often, manufacturers quote a car's "dry" weight (without driver, fluids, or fuel), a metric which bears no resemblance to its weight in working order.

Calculating a car's operational weight from it...

The test weight of the cars can vary a lot due to different options fitted to the car, for example Motortrend tested Aventador LP700-4 twice, first time they weighed it to 1731 kg and then 1863 kg. Motortrend stated in the last test that this was due to different options fitted.

 

[DataHunter]

Motortrend tested Aventador LP700-4 twice, first time they weighed it to 1731 kg and then 1863 kg.

That is extraordinary. I cannot imagine what 132 kg of options could possibly consist of.

 

[CrunchSlaughtered]

I have one assumption that is most probably wrong, but i think that the manufacturers are giving the lowest possible weight, which means that when there are options which decrease the weight like lighter rims, carbon-ceramic brakes, some carbon parts and lighter seats, the weight is shown with these options applied. The cars that I suppose are effected by this are BMW M3, M4, M5, MB AMGs and some Porsches

 

[bmwz4coupe]

I have one assumption that is most probably wrong, but i think that the manufacturers are giving the lowest possible weight, which means that when there are options which decrease the weight like lighter rims, carbon-ceramic brakes, some carbon parts and lighter seats, the weight is shown with these options applied. The cars that I suppose ar...

They should not do this, the weight the manufactor claim must be before ticking on the option list. If they claim weight with lightweight option they must specify this, and Ferrari and McLaren actually does this, 720S weighs 1322 kg dry and 1283 dry with lightweight options.

 

[Matski]

No, EU weight (and also the anerican curb weight I belive) is the weight of the car without any options. Many of the options will increase the weight of the car, like electric seats and sun roof. And some options will actually reduce the weight, like lightweight sportseat, rims or other carbon pieces.

That would make sense, but I thought the numbers had to be representative of real world specifications to avoid cars being listed with weights of 'stripper' versions...

... actually as I'm typing this, I might have read that in the context of fuel consumption, not weights. Ignore me.

 

[tristatez28lt1]

I have one assumption that is most probably wrong, but i think that the manufacturers are giving the lowest possible weight, which means that when there are options which decrease the weight like lighter rims, carbon-ceramic brakes, some carbon parts and lighter seats, the weight is shown with these options applied. The cars that I suppose ar...

Yes, certainly a possible reason but the weight difference is too much.

The heaviest option in a car is the sunroof at around 50-85 kg depending on size and functionality. Carbon ceramic brakes should be around 25-35 kg. Seats can be another 20 kg.

 

[CrunchSlaughtered]

They should not do this, the weight the manufactor claim must be before ticking on the option list.

In which directive is this written? I believe that the manufacturers are using every single legal (and sometimes not that legal, like VAG) possibility to show the best possible numbers, regardless if it is for fuel consumption, weight or exhaust emissions. If there is no legal prohibition, they are doing this for sure.

 

[bmwz4coupe]

In which directive is this written? I believe that the manufacturers are using every single legal (and sometimes not that legal, like VAG) possibility to show the best possible numbers, regardless if it is for fuel consumption, weight or exhaust emissions. If there is no legal prohibition, they are doing this for sure.

EUR-Lex - 32012R1230 - EN - EUR-Lex
Look article 2

 

[bmwz4coupe]

That would make sense, but I thought the numbers had to be representative of real world specifications to avoid cars being listed with weights of 'stripper' versions...

... actually as I'm typing this, I might have read that in the context of fuel consumption, not weights. Ignore me.

You may have a point there regarding the american market; I have read that manufacteurs when stating curb weight must include the options that 35% of cars normally have. I dont know if this still applies. In the european market it is for sure withouth options.

 

[DataHunter]

This is some excellent work done by members of this forum.

 

[DataHunter]

Good news! I made an Excel 2016 spreadsheet for easy calculation of standardized weights.

If I can figure out how to publicly post it, I will make it available to everyone.

Fuel tank capacity is in liters, and the cell is formatted so that the user may simply type in the number (i.e. "90" instead of "90 L").

Fuel level is pretty straightforward; the spreadsheet adjusts the level of fuel in the average weight (accounting for the fuel levels of each test standard) to that level specified by the user.

The confidence interval applies to the "weight range" calculation. The user will specify the level of statistical confidence, and the spreadsheet will then determine a weight range based on the specified confidence level and kerb weight data. For example, if the weight range says 1537.4 to 1556.6 kg with 99% confidence, we can be 99% confident that a random weight measurement (with the user-specified fuel level) will fall within that range.

As usual, all statistics are calculated on the fly in Excel, and results are shown immediately after the input of each data point.

 

[Giannis]

@DataHunter you may upload it via the "Resources" section of the site.

Many thanks for your time and effort!

 

[DataHunter]

Thank you! Will do!

Where is this section? I cannot seem to find it.

I see it mentioned here, though:

https://www.germancarforum.com/threads/resources.48695/

As soon as I can locate it, I will post the file.

 

[DataHunter]

Well, because I can't find the resources section, I've uploaded it to Google Drive. I've linked to a downloadable version of the spreadsheet below (remove parenthesis from the (com))

https://drive.google.(com)/open?id=1K5qNAGbwZnyh9f9QnS380f9gvrmSYcQl

 

[Giannis]

Thank you! Will do!

Where is this section? I cannot seem to find it.

I see it mentioned here, though:

https://www.germancarforum.com/threads/resources.48695/

As soon as I can locate it, I will post the file.

It's here: https://www.germancarforum.com/resources/

(4th button on the top menu)

You can then edit your resource or upload newer versions and thus keep it constantly updated. It's a nice feature!

 

[DataHunter]

It's here: https://www.germancarforum.com/resources/

I get an error, followed by the response "You do not have permission to view this page or perform this action."

 

[DataHunter]

I made some small updates to the Excel spreadsheet.


Some small corrections have been made to the calculations

I altered the units, so now you will input pounds (lbs.) for the American magazines (the units will show up after you type the numbers)
Fuel specific gravity has been altered slightly to be more realistic to 95 RON fuels commonly used by sports cars. (0.740 vs 0.755)
Uncertainty in the fuel density is also accounted for.


New link to current version: https://drive.google.(com)/file/d/1K5qNAGbwZnyh9f9QnS380f9gvrmSYcQl/view?usp=sharing

Remove the parenthesis in the URL.