weight / fuel economy study

shizzler

Veteran Member
Joined
Jun 25, 2005
Location
Ann Arbor MI
TDI
05 BEW Wagon
Nice link, thanks.

So they predict a 5% weight reduction (upper limit of what's easily achievable in an Mk4) would give 2.1% city and 1.4% hwy improvement for the small car with diesel engine. Seems pretty reasonable.

I was able to remove over 70 lbs from my Jetta by ditching my aftermarket 10" subwoofer & amp, and not caring how the trunk looks (trim removal). I was planning to make a separate thread sometime to list the weights of the components I weighed upon removal, eventually...
 

ChippedNotBroken

Veteran Member
Joined
Dec 29, 2004
Location
Pocono\'s, NYC
TDI
Jetta A4 1999.5 Green
Nice link, thanks.

So they predict a 5% weight reduction (upper limit of what's easily achievable in an Mk4) would give 2.1% city and 1.4% hwy improvement for the small car with diesel engine. Seems pretty reasonable.

I was able to remove over 70 lbs from my Jetta by ditching my aftermarket 10" subwoofer & amp, and not caring how the trunk looks (trim removal). I was planning to make a separate thread sometime to list the weights of the components I weighed upon removal, eventually...
SO.... If I lose 10lbs and leave my wife at home I can get better fuel economy :p
 

JASONP

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Feb 24, 2008
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Guelph
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2015 Golf TDI Comfortline 6spd
Hey Victor, I like you call letters

Tango Delta India
 

Victor-Whiskey

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Joined
Aug 26, 2010
Location
NEK VT
TDI
2015 Jetta TDI DSG
Nice link, thanks.

So they predict a 5% weight reduction (upper limit of what's easily achievable in an Mk4) would give 2.1% city and 1.4% hwy improvement for the small car with diesel engine. Seems pretty reasonable.

I was able to remove over 70 lbs from my Jetta by ditching my aftermarket 10" subwoofer & amp, and not caring how the trunk looks (trim removal). I was planning to make a separate thread sometime to list the weights of the components I weighed upon removal, eventually...

I removed my spare and jack (I am aware of the risks) and have a mini pump, tire slime, and puncture repair kit. Saved ~53lbs
 

Victor-Whiskey

Veteran Member
Joined
Aug 26, 2010
Location
NEK VT
TDI
2015 Jetta TDI DSG
Like a 12V mini pump? Have a link to what you purchased?

And a repair kit like this one?
http://autorepair.about.com/od/fixityourself/ss/tire_plug.htm

I am interested in ditching my spare tire also, but only after I get the right emergency equipment and feel confident that I could repair most problems.
Yep, similar to that. I don't have a link. It came from my old BMW; they stopped using spares in some cars years ago to save weight.
 
Last edited:

Kenny D

Active member
Joined
Sep 3, 2010
Location
Houston
TDI
2010 Jetta
Like a 12V mini pump? Have a link to what you purchased?

And a repair kit like this one?
http://autorepair.about.com/od/fixityourself/ss/tire_plug.htm

I am interested in ditching my spare tire also, but only after I get the right emergency equipment and feel confident that I could repair most problems.

My brothers boss owns a VW dealership and has told me that the rear crash test safety rating was achieved by having a full size spare in rear to absorb the impact of a 45mph hit from the rear (what they are tested at). You are not only losing piece of mind but you are losing safety also. It was placed there for a reason.
 

ChippedNotBroken

Veteran Member
Joined
Dec 29, 2004
Location
Pocono\'s, NYC
TDI
Jetta A4 1999.5 Green
I suppose if there are passengers in the back seats it might make a difference, otherwise if you are hit hard enough in the rear to reach the front seats I doubt the tire being there would have made much difference.
 

Victor-Whiskey

Veteran Member
Joined
Aug 26, 2010
Location
NEK VT
TDI
2015 Jetta TDI DSG
My brothers boss owns a VW dealership and has told me that the rear crash test safety rating was achieved by having a full size spare in rear to absorb the impact of a 45mph hit from the rear (what they are tested at). You are not only losing piece of mind but you are losing safety also. It was placed there for a reason.
It's held in place with a plastic screw with a movable cover over it...
I am an aircraft engineer and I believe it does little to nothing in a rear collision. Is there a remote chance I might have a blow out one day and be stuck for hours, yes. But I'm an enthusiast and it's a risk I take.
 

ChippedNotBroken

Veteran Member
Joined
Dec 29, 2004
Location
Pocono\'s, NYC
TDI
Jetta A4 1999.5 Green
My sisters brothers aunt told me that her cousins uncles brother-in-law knew the wife of an engineer that might have worked on the spare tire in my car, and she said it was okay.
 

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member
Joined
Jun 20, 1998
Location
Sterling, Massachusetts. USA
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none, 2014 Chevy Volt, 1988 Bolens DGT1700H
I'm dubious anout the relative merit of the conclusion reached in the 'study'.
OK, not so much the conclusion, but the appearance of data to back up what is known.
Yes a lighter mass will accelerate and brake with less energy input, but the producers of the study add a second variable by 'downsizing' their simulated engines used with their simulated lighter cars. (slides 16 and 17)
They then use 'downsized' engines to maintain "acceptable" acceleration rates, not match simulation acceleration rates. (slide 28)
Because of these inconsistencies, I can't accept the conclusion that weight accounts for the amount of fuel savings (which is less than 1% as steady top gear speed, despite smaller engines and lesser performance).
 

jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
I'm dubious anout the relative merit of the conclusion reached in the 'study'.
OK, not so much the conclusion, but the appearance of data to back up what is known.
Yes a lighter mass will accelerate and brake with less energy input, but the producers of the study add a second variable by 'downsizing' their simulated engines used with their simulated lighter cars. (slides 16 and 17)
They then use 'downsized' engines to maintain "acceptable" acceleration rates, not match simulation acceleration rates. (slide 28)
Because of these inconsistencies, I can't accept the conclusion that weight accounts for the amount of fuel savings (which is less than 1% as steady top gear speed, despite smaller engines and lesser performance).
Yeah, that really changes the "results". I usually carry over a hundred pounds of golf equipment in the trunk and my mileage doesn't change noticeably at all with or w/o it, but most of mine is highway miles. Starting/stopping maybe it would, because lighter is easier to get rolling, og course. (Objects at rest...etc)
Who was the funder of the study?? The aluminum.org guys? Results usually tend to favor the funder, IMHO.
 

glitdi

Veteran Member
Joined
Dec 28, 2009
Location
West Coast Canada
TDI
Tdi asv motor in a mk3 golf, om642 in a wk jeep
If someone needs a guinea pig for weight enhancement as opposed to weight reduction I consistently carry probably about 50-70 lbs in the boot of my car.
I still get fantastic mileage when I try.
(try is the keyword)
Also the added wieght of my wheels surely has effected my mileage by a few liters per 1000 k
 

ruking

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Mar 27, 2003
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San Jose area, CA
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2003 VW Jetta, 5 M, Reflex Silver: 09 Jetta, 6 Sp DSG, Candy White: 12 VW Touareg, 8 Sp A/T, Flint Gray
I have read in passing and also found this to be true: the rule of thumb is for every (+/- 100#'s), there is a delta of (+/-) 1 to 2 mpg.
 

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member
Joined
Jun 20, 1998
Location
Sterling, Massachusetts. USA
TDI
none, 2014 Chevy Volt, 1988 Bolens DGT1700H
Stop and go: I absolutely agree.
Steady state: The difference is negligible to the point of being obscured by normal variation.
 
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