tips for fuel economy

deltatech

Veteran Member
Joined
Jun 25, 2007
Location
Jefferson NJ
TDI
2004 Jetta TDI
My sympathies with you TdiNC. I've had my 2004 Jetta TDI with the BEW engine since 35K miles. Used to get 45 mpg no matter what. Had an accident and now my best is 40mpg. If I ever figure it out I will post it here.
 

TdiNC

Veteran Member
Joined
Jun 22, 2012
Location
NC
TDI
2004 Golf 4 door TDI 5-speed
* What sort of driving do you do (highway or city)?
* How long are your average trips?
* What is your highest highway cruising speed if you do highway driving?
* Have you checked your tyre pressures (& what are they?)
* How wide are your tyres, and how big are your rims?
* Do you have any roof rack / trailer?
* If you put your hand onto the wheelnuts after a long drive, do any of them feel hot? (the fronts should be warm, and the back ones should be cold, and even temperature side-to-side).

1. It is my only car and I drive average 120 miles (total) on the weekdays to and from work. Its a mixture of hwy and city. Weekends however, I am generally on a 3 hr drive hwy (approximately 200 miles one way).

2. 10-15 min weekdays and 2.5-3 hrs one way on weekends.

3. Hwy speed between 70-80 miles per hour.

4. I will get back with the tire pressure.

5. 15 inch wheels (I have hubcaps atm, will be putting on a friends 17inch audi tt stock wheels here in the near future.)

6. I do have a Thule roof rack on top as well.

7. Will check lug nut temp after i get home from work.

Even with some of the bad stuff like roof rack and high speed hwy driving don't you think I should be getting better diesel mileage?

Please let me know what you think. Thanks a whole bunch!!!
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
...

1. It is my only car and I drive average 120 miles (total) on the weekdays to and from work. Its a mixture of hwy and city. Weekends however, I am generally on a 3 hr drive hwy (approximately 200 miles one way).

2. 10-15 min weekdays and 2.5-3 hrs one way on weekends.
The 10-15 minute trips will be having a penalty since the engine won't have warmed up yet. But the engine will be nice & hot during the weekend trips so that should make up for it.

3. Hwy speed between 70-80 miles per hour.

4. I will get back with the tire pressure.
The really important thing is to make sure they never drop below the recommended pressure while the tyre is still cold. Some people (including myself) run with higher pressures, but this is a trade-off between comfort & economy (the ride is much harsher at high pressures). Also, cheap Chinese tyres will bulge & wear on the centre if the pressure is high. Premium tyres handle high pressure well.

5. 15 inch wheels (I have hubcaps atm, will be putting on a friends 17inch audi tt stock wheels here in the near future.)
The 15" wheels are good for MPG, you will notice they will drop a little once you put the 17s on.

6. I do have a Thule roof rack on top as well.

7. Will check lug nut temp after i get home from work.

Even with some of the bad stuff like roof rack and high speed hwy driving don't you think I should be getting better diesel mileage?
Well, with a roof rack on while doing highway trips at a peak of 80... the aerodynamic drag will be terrible hence low MPG. So I think your MPG is reasonable under the circumstances. If you have space to store your stuff in the boot/trunk/back-seats instead, then you should see your highway MPG improve, particularly if you drop down to 75 or 70 at the same time.

Please let me know what you think. Thanks a whole bunch!!!
 
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deltatech

Veteran Member
Joined
Jun 25, 2007
Location
Jefferson NJ
TDI
2004 Jetta TDI
I got 36 mpg for my last 2 tanks. I increased my tire pressures to 42-44 psi each and put the engine cover back on the bottom of the engine and my fill up today was 39.6 mpg.
 

Dewfini

New member
Joined
Jun 3, 2012
Location
California
TDI
2000 Golf
anybody have any experience with the K&N re-usable air filters? got one on my 2000 TDI golf 5 speed (241,000K) didnt really notice any fuel economy increase. the car stayed at its current 56 MPG when i installed it.
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
More likely to ruin your maf due to oil contamination and hence drop your mpg
 

Sfkjeld

Active member
Joined
Jun 16, 2012
Location
San Francisco
TDI
2012 Sportswagen 6sp
Tips for driving technique

Have a 2012 6sp manual JSW. Wondering whether to pay attention to the gear shift indicator for maximizing mpg. It will suggest driving at 1000rpm. Seems awfully low.
 

Jettadoor

Veteran Member
Joined
Jul 2, 2009
Location
Neuville P.Q. Canada
TDI
2000 Auto 419,000Km. +/-(260,000miles)
Make sure you are a safe distance back before drafting (2 seconds minimum), particularly if your nearest&dearest are in the car... (however if you are giving a lift to a bunch of tax inspectors, please feel free to draft as near as you like :) )
If I could get a few bank managers into the car I would try and get into over-draft :)

I have always understood that maximum efficiency is situated in the general area around the peak of the torque curve. I.E, for the TDI between 1800-2200 RPM. If memory serves me that is where the best fuel consumption will be, at least for highway driving. This puts you around the legal limit with the gearing on my auto trans.

If there is a way to log mg/stroke in real-time on VCDS it would be possible to run several tests and calculate fuel consumption for different scenarios. I have some time on my hands and that could be an interesting project when I have my VCDS.

A couple of things I do with the A/C is to use it going down hill when I have to lift the throttle a bit and I use it when I have to slow down; downshift to keep up the revs and the pump will help slow the car down.
I think this uses absolutely no extra fuel and sometimes it is enough to cool down the ducts a bit so they don't warm up the incoming air. Free lunch. Even on a hot day I turn it off going up-hill and when stopped at a light or in parking lots.

I am thinking of a set of new nozzles at 250,000 miles and I hope that will be beneficial to fuel economy. I'm not sure when or if the nozzles were done on this car.

Best thing I read about fuel economy stressed the importance of defensive driving; reading the road ahead and seeing what the traffic is doing a few cars in front of you. If you only have to slow down instead of stopping you use less fuel to get back up to speed. Leave as much space as possible to the car in front so you don't have to brake too hard if things slow down up front. Turning fuel into brake dust is the modern day alchemy but brake pads can cost the price of a tank of fuel.

Just a couple of my jumbled thoughts on fuel economy....
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
...
I have always understood that maximum efficiency is situated in the general area around the peak of the torque curve. I.E, for the TDI between 1800-2200 RPM. If memory serves me that is where the best fuel consumption will be, at least for highway driving. This puts you around the legal limit with the gearing on my auto trans.
...
When you are steadily cruising at a reasonable speed you aren't using a lot of horsepower, and you won't be at the BSFC peak.

If you *were* driving at your peak at the right RPM, you'd probably have to be climbing a mountain :)

When you look at the BSFC chart, you need to find the best BSFC figure *for the horsepower you need*. For highway driving, you won't be able to use that optimum RPM because it will probably be too slow even if you have a very tall top gear (which is where the highway 'slowest reasonable speed in your highest gear' rule comes from).
 
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TDi Erik

Member
Joined
Sep 15, 2011
Location
San Jose, CA.
TDI
2005 Passat TDI PD
+5 MPG by removing intake duct

I have been chasing down low mileage since I bought my Passat last year. My Passat has the BLOCKED front grill where the air intake duct attaches.

See: http://i227.photobucket.com/albums/dd204/tchivers/fbbe_3.jpg

Here is the complete thread,
http://forums.vwvortex.com/showthread.php?2126117-Factory-Passat-ram-air

I removed the intake duct and the two other ducts in the lower left corner of this picture. My highway mileage has improved by at least 5MPG according to the instrument panel MPG gauge. I wont know the actual number until my next fill-up.

Eventually I'll cut out each little rectangle in the grill but that project will have to wait for not.

Cheers,
Erik
 

jonbolden

Member
Joined
Oct 24, 2012
Location
Austin, TX
TDI
2004 Jetta Wagon TDI
The original post mentioned gunning the gas and seeing a cloud of black smoke as an indication of car health. I noticed my does a cloud of smoke every single time. My mechanic just did a preventative cleaning of carbon buildup with my throttle block. Could that mean that I need to take it on some aggressive drives more often?

This thread is super useful, thank you!
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
It will benefit from an occasional 'italian tune'. On my old Passat I used to do this once every second tank (2000 miles or so). Wait until the engine has fully warmed up, and then drop down into 4th on the motorway and blast up a steep hill for 30s or so. Glance in the rear-view and you should see the smoke. Repeat it on another hill and the smoke should no longer be there.

It's mostly relevant to cars which have a variable vane turbo (VVT). From what I understand all the NA TDI's have a VVT?
 
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TonyJetta

Top Post Dawg
Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
From what I understand all the NA TDI's have a VVT?
Actually, the VNT (VVT) turbos for NA didn't show up in TDI's, until 99.5, with the A4 chassis. Prior to that the turbos were old-school wastegated.

Tony
 

Itsjustmetal

Active member
Joined
Nov 19, 2012
Location
Seattle
TDI
2010 JSW TDI
Hey guys how's it going. I see how you guys are posting that you are getting mid 40's-50's se even mid 50's. for the life of me it seems as if I can't get over 38mpg. From my last calculations I got roughly 34mpg. I just recently picked the car up. 2010 JSW with DSG and has 72,000 miles on it. Car has factory 17" wheels and tires (37psi) and I do mostly highway. 25 miles each way with about 5 miles of city at the the beginning and end of each way. I feel like I should be getting in the low 40's and definitely not low 30's. any suggestions?
 

Itsjustmetal

Active member
Joined
Nov 19, 2012
Location
Seattle
TDI
2010 JSW TDI
Do these cars get bad carbon build up? What's the best way to clear it out besides hammering down for a few seconds? How often should this be done?
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
... I see how you guys are posting that you are getting mid 40's-50's se even mid 50's. for the life of me it seems as if I can't get over 38mpg. ...
The highest figures are coming from vehicles with the following:
* Manual transmission not auto or DSG
* ALH engine
* Longer journeys than yours
* More motorway miles than yours
* Smaller rims than yours (and maybe narrower)
* Earlier year than yours (the 2010 is a lot heaver than the 1996 for example).
 

TonyJetta

Top Post Dawg
Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
Hey guys how's it going. I see how you guys are posting that you are getting mid 40's-50's se even mid 50's. for the life of me it seems as if I can't get over 38mpg. From my last calculations I got roughly 34mpg. I just recently picked the car up. 2010 JSW with DSG and has 72,000 miles on it. Car has factory 17" wheels and tires (37psi) and I do mostly highway. 25 miles each way with about 5 miles of city at the the beginning and end of each way. I feel like I should be getting in the low 40's and definitely not low 30's. any suggestions?
All the factors Mike mentioned, are indeed working against you.

However, I have noticed a few things about the DSG that might help you.
1) My wife drives in Sport mode (at my request). She won't shift it manually. She averages 32-36mpg.
2) I drive the car in manual mode. Around town, on the freeway, it's always manually shifted. I'll average 36-41mpg (summer v. winter)

I suggest you manually shift that DSG. Keep it under 2500rpm until the water temp is about 1/4way up the gauge (140F or so). After that, shift at 3000-3200rpm. Use part throttle or full throttle, it doesn't seem to matter much.

Do these cars get bad carbon build up? What's the best way to clear it out besides hammering down for a few seconds? How often should this be done?
At least once a week, or more frequently, get on the throttle in 3rd and/or 4th gear when merging on the freeway. And, I mean FULL THROTTLE. This will ensure the turbo vanes are exercised to their full range of motion. BTW...this is also called an Italian tune up. ;)

Tony
 

Itsjustmetal

Active member
Joined
Nov 19, 2012
Location
Seattle
TDI
2010 JSW TDI
Thanks Tony. I never drive over 2200 until the car comes up to temp. I have has a handful of non diesel vw's and that's how I have always gotten them up to temp. Never have let any of my cars idle for to long. Jump in and go. I may look into different tires but I also my switch over to snow tires (which I know will kill my mpg) but also going to go narrower than stock.

Ill make sure to really see if I can blow out the carbon and see if that helps. I am also going to get he oil changed, check the filter and prob replace the fuel filter when I get home from vacation.
 

rockiefan17

Active member
Joined
Dec 3, 2011
Location
Fort Collins, CO
TDI
2003 Jetta TDI
So what would say my 03' Jetta TDI (VE) should be getting MPG wise? I take alot of 15min trips at 55-60mph. I was getting 36-40mpg. I recently rebalanced and rotated tires and took an extended trip with some steep mountain driving and was able to get 44mpg. I am running without a lower engine cover or bellypan if you will (replaced it twice because of the snow and ice buildup in this great state of colorado, didnt want to pay for another). I used to get 45-50+mpg back in 2006 when I bought it. Alignment is good, thermostat is new, MAF good, Brakes in great shape, driving style i think fits the bill for normal easy driving with occasional italian tune ;), turbo new, Wouldnt know about the timing hopefully mech did it right lol. Roughly 130,000 with timing belt at 95,000.

Been looking at an metal belly pan, EGR cleanout, performance injectors, messing with a chip or scantool with the help of a pro.... But if im getting close to what to what I should I dont want to waste my money. Would love to see 50+mpg again tho.
 
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MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
Those are pretty short trips, and hence you'd get low MPG. Were you doing short trips when you originally bought it?
 

NWFLYJ

Veteran Member
Joined
Oct 4, 2012
Location
Pensacola
TDI
03 Jetta
I am running without a lower engine cover or bellypan if you will (replaced it twice because of the snow and ice buildup in this great state of colorado, didnt want to pay for another). .
I feel for you on the belly pan, but it is a line of defense for the oil pan. Just a thought. Mark
 

Woodrobin

Veteran Member
Joined
Jun 21, 2010
Location
Topeka, KS
TDI
2001 Jetta GLS
Been looking at an metal belly pan, EGR cleanout, performance injectors, messing with a chip or scantool with the help of a pro.... But if im getting close to what to what I should I dont want to waste my money. Would love to see 50+mpg again tho.
The skid plate (metal belly pan) is a good choice, bordering on a must-have. I had a car with a Dieselgeek plate, and have one now with an Evolution plate, and I believe they're both excellent products.

EGR cleanout can can help restore proper respiration to the engine, and should have a positive effect on fuel efficiency. Not a bad idea to check the snow screen (if you haven't already removed it) and the air filter to make sure all passages are clear.

Here's how I test the air filter (for what it's worth): take a clean dish towel or piece of white paper towel and lay it on the driveway. Take the air filter out of the filter box, hold it level about chest high over the towel, and drop it. If the towel has any significant amount of dirt or chunks on it after you pick up the filter, you need a new air filter. The reason this works is that the dirt would be coming out of the outgoing, not incoming, end, and that indicates a saturated filter.

Do you have the updated MAF sensor? Those help, too. If in doubt, take a look: if it has a tube with a grill over it inside the main tube, it's the new part. If there's a tower-like projection into the middle of the main tube, with no grille, it's the old part. If the car runs as well or better with the MAF unplugged, you need the new part, because the old one is shot.

Personally, I'd do those steps and check for changes to fuel economy, then move on to a tune and/or injectors if you haven't hit the desired MPG mark. It's amazing what easy breathing can do for efficient combustion. :)
 

livewires250

Member
Joined
Nov 4, 2012
Location
Ohio
TDI
2010mkv jetta sedan
I have a 2010 TDI jetta S, with DSG, normally drive in 'D' range,averages 40 MPG. 11/22/12, an hour commute netted me 46 mpg according to the MFD,16" tires.
 

rockiefan17

Active member
Joined
Dec 3, 2011
Location
Fort Collins, CO
TDI
2003 Jetta TDI
Those are pretty short trips, and hence you'd get low MPG. Were you doing short trips when you originally bought it?
I bet my average trip was 20-30miles when I bought it. I got 50-55mpg for a solid 6 months after I bought it then a slow steady decline. I blamed it on the sulfer decrease but now im unsure.

The skid plate (metal belly pan) is a good choice, bordering on a must-have. I had a car with a Dieselgeek plate, and have one now with an Evolution plate, and I believe they're both excellent products.

EGR cleanout can can help restore proper respiration to the engine, and should have a positive effect on fuel efficiency. Not a bad idea to check the snow screen (if you haven't already removed it) and the air filter to make sure all passages are clear.

Here's how I test the air filter (for what it's worth): take a clean dish towel or piece of white paper towel and lay it on the driveway. Take the air filter out of the filter box, hold it level about chest high over the towel, and drop it. If the towel has any significant amount of dirt or chunks on it after you pick up the filter, you need a new air filter. The reason this works is that the dirt would be coming out of the outgoing, not incoming, end, and that indicates a saturated filter.

Do you have the updated MAF sensor? Those help, too. If in doubt, take a look: if it has a tube with a grill over it inside the main tube, it's the new part. If there's a tower-like projection into the middle of the main tube, with no grille, it's the old part. If the car runs as well or better with the MAF unplugged, you need the new part, because the old one is shot.

Personally, I'd do those steps and check for changes to fuel economy, then move on to a tune and/or injectors if you haven't hit the desired MPG mark. It's amazing what easy breathing can do for efficient combustion. :)
Ill look into the metal plates.

Air filter is good, pretty sure ive got the new MAF (damn expensive part) I replaced 18months ago (I lost a ton of power when this went out) but ill look at it again.

Im still kinda wondering what the standard or average is for mpg on these cars? is 44 low? should I be getting 50?
 
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vdubtdi11

Well-known member
Joined
Feb 8, 2012
Location
NoVA
TDI
2011 golf TDI
What do you guys think about fuel economy in warm vs. cold temps? I can drive from DC to NJ in the warm months and I can get 55 doing [around] the speed limit and the same trip and same yesterday, in the 40's and 50's outside, I only averaged 45mpg. Forgive me as this is probably a DUUUHHH question, but is that normal?

additionally, my stepfather said that many service shops let your tire pressure down to a lower number for the 'ride'. Is that true? I already had to ask them not to run my pristine gloss black paint through the auto car wash with dirty brushes, which they did anyway.. Cant they just give me what I am there for?
 

WutGas?

Veteran Member
Joined
Feb 28, 2012
Location
Oklahoma City
TDI
The Last Real Jetta Sedan
Cold weather = cold weather fuel and longer warm up times. This definitely plays a role in MPG.
 

MikeMars

Veteran Member
Joined
Mar 6, 2008
Location
UK
TDI
Vento 1.9 TDi (retired), A4 1.9 TDi (rear end collision), VW Passat 1.9 TDi (retired), Audi A2 1.4 TDi
... Forgive me as this is probably a DUUUHHH question, but is that

...many service shops let your tire pressure down to a lower number for the 'ride'. Is that true? ...
Yes and yes. My mpg has dropped like a brick again this winter, which I find depressing but inevitable.

They will drop your tyre pressure to the one on the label, basically for legal reasons (ie nobody can successfully get sued for following the manufacturers recommendation). Expect it. Unlike putting your car through the machine cleaner, which is simply poor service as a result of doing things by rote.
 
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Dieselmad

Well-known member
Joined
Sep 22, 2011
Location
Fochville, South Africa
TDI
Jetta MK4 1.9Tdi,
Brakes: many Volkswagens, especially A4 platform cars, have chronic stuck parking brake cables. This causes the rear calipers to drag, and your torquey diesel won't know it... it 'll just eat more fuel to move the car down the road. Also, brake pad perches can rust up, and cause the pads to sieze in their spots, dragging the brakes.

I think my car(2002 Jetta 1.9Tdi) is suffering from this. Lately i only get 30 MPG whereas i normally averaged at 35 MPG under mixed driving conditions. My personal best was 50 MPG long distance doing 74.5 Miles per hour. What i also found is that my left rear wheel had a slow puncture. Slow puncture is fixed now but i noticed that my rear brakes get hot after a normal short distance traveled. I also noticed that my hand brake/park brake lever is stiff when i pull it up. Is there any remedy's to fix this, any links perhaps? Thanks in advance.
 
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