Why did the mileage performance degrade in later TDI models?

repoman

New member
Joined
Nov 15, 2010
Location
New Jersey
TDI
1998 Jetta, 2000 GLS (auto), 2002 GLS (Manual)
I used to get about 48 mpg in my 2003 Jetta TDI now I am looking at buying another TDI and the mileage performance is much lower? do I need to take the fuel control to an aftermarket performance shop and have the software tweaked?
 

slamhouse

Veteran Member
Joined
Oct 3, 2011
Location
Stanwood, WA
TDI
2006 Jetta TDI SE
on the newer tdi models, i believe theres more emmisions restrictions on the motor like the DPF. maybe others will chime in with more knowledgable info.
 

JSWTDI09

Top Post Dawg
Joined
Jan 31, 2009
Location
Las Vegas, Nevada
TDI
2009 JSW TDI (gone but not forgotten)
There are several reasons:
The new engines are bigger and more powerful. Power takes fuel.
More emissions equipment requiring extra fuel to regenerate.
The newer VWs are bigger and heavier.

All things considered, it's rather amazing that their fuel economy is as good as it is.

Have Fun!

Don
 

snakeye

Veteran Member
Joined
Dec 13, 2009
Location
Montreal, Canada
TDI
2003 Jetta and Wagon, GLS 5sp
The overall efficiency of the new CR engines hasn't dropped that much, if any, considering the performance increase over the ALH and BEW engines.
 

GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
Don't forget the major change in published EPA numbers in 2008.

The Mk5 vehicle platform is heavier than the Mk4 and is burdened with more emission controls.

And as noted above, the Passat is currently the way to go. Yes, it will need an occasional swig of AdBlue (diesel exhaust fluid) but that allowed them to recalibrate the engine for better fuel consumption, and owners of the new Passat TDI with manual transmission are reporting remarkable consumption figures. Although that car is physically bigger than a Mk5 Jetta, it is about the same weight.
 

Forza91

Veteran Member
Joined
Dec 23, 2011
Location
San Diego, CA
TDI
2003 Jetta GL TDI, 2004 Golf GLS TDI
Yeah I don't know the technical stuff, but in a nutshell fuel efficiency is lower because the cars keep getting bigger, plus people can't seem to live without all of their creature comforts -they don't run on nothing. the new Jettas are roughly comparable in size to the older B5 Passats. Then add all the emissions standards.
 

tdi90hp

Veteran Member
Joined
Feb 5, 2002
Location
Canuckland
TDI
2011 Golf TDI 6 speed(gone but NEVER forgotten)
Don't forget the major change in published EPA numbers in 2008.

The Mk5 vehicle platform is heavier than the Mk4 and is burdened with more emission controls.

And as noted above, the Passat is currently the way to go. Yes, it will need an occasional swig of AdBlue (diesel exhaust fluid) but that allowed them to recalibrate the engine for better fuel consumption, and owners of the new Passat TDI with manual transmission are reporting remarkable consumption figures. Although that car is physically bigger than a Mk5 Jetta, it is about the same weight.
ya...drive a boat...get good mileage...makes sense...the Golf should get better mileage....If I have to drive a Passat I wont drive a VW
 

GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
The Golf Mk7 will probably get better mileage. It's supposed to lose some weight (back to same as Mk4) and it's getting the new EA288 engine with a number of refinements, which should help. It isn't known if they're going with the AdBlue system on that engine yet.

(The new Passat is too big for me and looks too much like an Impala, but it is very good on fuel and it won't get a frozen intercooler ...)
 

truman

Top Post Dawg
Joined
May 18, 2000
Location
columbia,MO,usa
TDI
'05 Passat Variant, Still miss the 03JW
So I would suppose that the Sportwagon MQB model will follow about a year after the Golf intro?
 

pknopp

Veteran Member
Joined
Nov 29, 2011
Location
WV
TDI
2012 Jetta Sportwagen
I always get better mileage than is listed. All of the things noted is why in general it's not going to do as well as certain older models but you still do pretty darn well.
 

TiggyTDI

Well-known member
Joined
Mar 28, 2012
Location
Southeast
TDI
TDI
I believe the sticker on my 12 TDI says 42 on the highway.....we are enjoying right around 50...so it's not as low as the sticker looks.---Mike
 

Grievous Angel

Veteran Member
Joined
Oct 22, 2011
Location
Tuscaloosa, AL
TDI
2012 Jetta TDI (traded after Diesel-Gate)
Fuelly indicates the older Jettas do indeed do better. But as others have stated, the current models are bigger and more powerful.

Having said that, I'm beating the EPA estimates easily, averaging around 45mpg in 80% highway driving.
 

Max Period

Veteran Member
Joined
Dec 30, 2010
Location
Toronto Ontario Canada
TDI
2011 Jetta Comfortline
Here I'm tallied the fuelly averages of 2009+ Jettas, 2004-2006 Jettas, 1998-2003 Jettas, and 2012 Passats.

Average L/100 km, weighted on distance driven, fuelly US MPGs for higher precision.
2009+: 6.198
2004-2008: 5.737
1998-2003: 5.440
2012 Passat: 5.837

Fuel consumption difference (compared to 1998-2003 Jetta):

2009+: +13.93%
2004-2008: +5.46%
1998-2003: +0.00%
2012 Passat: +7.28%

Fuel consumption difference (compared to CR Jettas)

2009+: +0.00%
2004-2008: -7.44%
1998-2003: -12.23%
2012 Passat: -5.84%
 
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TheHolyCobra

Well-known member
Joined
Sep 7, 2008
Location
Ohio
TDI
'01 Jetta
There are several reasons:
The new engines are bigger and more powerful. Power takes fuel.
More emissions equipment requiring extra fuel to regenerate.
The newer VWs are bigger and heavier.

All things considered, it's rather amazing that their fuel economy is as good as it is.

Have Fun!

Don
+1 to everything here.

Take a look at some of the cars that have *cough* had their exhaust parts simplified *cough* and you will see a DRASTIC improvement in gas mileage.

Keep in mind that a DPF uses extra fuel to clean itself out as well.
 

Hansgruber

Well-known member
Joined
Mar 23, 2012
Location
New Jersey, US
TDI
2006 TDI
The new Passat is also more aerodynamic than the A5s. If you are on the highway the Passat is the way to go. If your commute is city, go Golf. My issue with the Golf is the purchase price. Each time I bought a TDI, I wanted to buy a Golf. Each time, I found the Jetta (my A4 was a wagon) to be the better buy. The Golf is a higher demand car. The dealers in my area never had them on hand. You needed to order and forget trying to talk the price down.

The other factor is room.

IIRC, the A3 and A4 had smaller frontal areas than the A5.
 

spryl001

Member
Joined
Apr 30, 2012
Location
Buffalo
TDI
2002 Jetta GLS TDI
I've been trying to decide if I wanted to get another MK4 or buy a little newer and go for an MK5 and have been wondering about this exact mpg situation. I do a lot of highway driving over 600 miles but also drive in a busy city when I'm going too school. I can't decide!!!!
 

OhhMan

Member
Joined
May 5, 2012
Location
Nelson BC Canada
TDI
91 or 92 Jetta ?
whoopee just full refueled my 91 jetta diesel and the figures show tdi on line 50 mpg imp mine came to 48 - this is mountain country
happy happy
it will pay for itself compared to my old astro van
just moved the mirror down onto dash so i can get better visibility
yrs
 
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