Newbies and Vets: Tips for better fuel economy!

the beave

Well-known member
Joined
Aug 19, 2015
Location
seattle washington
TDI
2015 Jetta TDI S
I've thought about doing a list like this for a long time. I remember when I first started driving my 1997 Jetta TDI I saw people claiming 50+ MPG. I figured they were off their rocker because I was only getting 36 if I was lucky. I fueled at Flying J (Now Loves) in Troutdale, Oregon, ran my tire pressure at 32, and drove like I stole the thing. Over the course of over 11 years and 500,000 miles of driving TDIs later I consider myself by no means an expert, but I'd like to consider myself a very well informed driver. The following is a list that people are welcome to add to. Rules and my top 10 list might be added to and changed as well as time goes on. The point is to get a discussion going so that those that are new to our community aren't intimidated with the fuel economy numbers they are getting, as well as meaningful ways on how to get better economy.

Some rules of thumb:

Rule #1: Never trust the computer--not even a $80,000+ avionics package in an aircraft is 100% accurate with regards to the computer. (For what it's worth, general aviation fuel gauges are required by law to be accurate at only one time--empty).
Rule #2: If you want to know your mileage, fill up completely to the top every time, this is after letting all the foam settle. Take miles driven and divide by x.xxx gallons (in the US) to get MPG. If you want to be very anal you must realize that if your wheels/tires are different than stock then your calculation can be off by 1-8%+. From the factory your speedo is off by ~3 MPH but your odometer is spot on. Remember that when putting on new tires, oversize tires will make your speedo more accurate, but your odometer will start to under report. My MK3 Jetta with 195/65/15 tires was perfect on the speedo, but the odometer was low by 6%.

I've been married since 29 Sept 2007. When I first met my wife she stated that her previous car got "X" MPG, which she always got off the computer display. She had a car without a computer and I had to teach her how to do MPG. She kept resetting the trip odometer when she went places to "see how far she goes." Point is that with her car which was supposed to get 28 MPG, she's had some tanks as low as 19.6 MPG. Since I first wrote this thread 6-years ago (update Oct 2014) she's had a Jetta Wagon and a Passat Wagon, she has become quite adept at calculating mileage too :).

This all brings us to:
BB's tips for higher mileage*, more or less in my order of easiness and cost effectiveness, and according to my own experience--I have multiple tanks in a row with over 60 MPG. I'm also one of the very few members to get 900 miles in a tank WITH A MK3 (15 gallon tank when dry). Driving for mileage is hard to do unless you know what to do--again YMMV:
1) Run tire pressure at 90% of recommended max pressure as stated on side of tire. (Free)
2) Run a good quality fresh fuel with a high cetane number (see bottom of post for some stations cetane numbers). In the west Chevron seems to by far bring the best numbers. A poor quality fuel with low cetane will lower MPG by up to 5. Just because it's a truck stop it usually means you are putting crap in your tank (especially Flying J). In the Midwest BP/Amoco are great--both BP and Chevron have stated that they won't have Cetane under 49, which is what our cars need. If you're filling with crappy fuel run an additive. I personally like Lubromoly Super Diesel Additive. There are lots of writeups online of differing qualities of additives. Biodiesel up to B20 won't really have an effect on your mileage. B100 will lower it by ~5 MPG. Note that these numbers are taken with over 750,000 miles of careful calculations over the course of many years, different cars, and different seasons.
Example: If you get 40 MPG from Flying J at $4.25/gallon, and 45 MPG from Chevron/BP at $4.49/gallon, you are paying $.10625/mile with the J, and $.09978/mile with the higher quality fuel. (And if you find a quality station next to a truck stop often the difference in price is less than $.05/gallon!) You actually save $64 just in fuel over the course of 10,000 miles by buying the more expensive fuel. This says nothing for what you might save in maintenance (injection pump and the rest of the fuel system) over the course of time. Just because it's expensive doesn't mean it's good. I've called lots of corporate offices and have numbers on the following cetane levels*** (See end of post)

Most truck stops are going to be low numbers because most semi's run the same regardless of cetane number.
3) Have a good working Mass Air Flow sensor and clean filters/snow screen & non-restrictive intake. (Air filter ~$14-20 for cold region filter--run it regardless of location. $20-30 for a good fuel filter. A poorly working MAF will give you 5+ less MPG. If you are in doubt to if yours is working, unplug it and see if you have more power. If you do, your MAF is bad. If you are running a cone filter (like K&N) you don't even have to check it, it's probably bad already. A stock air filter flows better than a K&N and it won't kill your sensor. A new Bosch revision "C" MAF will run about $100 for a 1999-2003 car, and about $160 for a 2004+ car.
4) Go easy on the accelerator. Drive like you have an egg under your foot. Bear in mind that when you are coasting in gear you use no fuel until you decelerate to ~1200 RPM. You burn ~.5 quarts per HOUR with a warm engine at idle, turning your car off at lights to save fuel is generally ineffective. *I rented a BMW 520D in Germany in September of 2014. It had auto stop/start. My feelings are that when the computer controls the stop start it's going to be more effective in fuel savings then you will be doing it manually. ;) Be gentle on acceleration--if you have a boost gauge limit your boost to 5 lbs. while speeding up. There is a lot of talk about city vs highway driving. A lot of people seem to confuse city driving with slow driving - what they fail to realize is the effects on your MPG are totally different between the two. The reason city MPG is low is because you have lots of stop and go; when you are accelerating you are using a lot of fuel. A cold engine also is less efficient than a warm engine. Furthermore every time you hit the brakes you waste precious kinetic energy (speed) which cost you fuel to build up...unless you are an expert at timing lights. This cycle continues to repeat itself from stopping point to stopping point. Because of this you see low MPG. Slow (constant/rural road) driving is optimal, since you can cruise for a long time in a high gear (low RPM) without much throttle at all due to the lower amount of wind resistance (aerodynamic drag) from trying to slice through the air at a lower speed. The result is excellent MPG. Highway driving is the median MPG; you can cruise at a constant speed in the highest gear, but you are traveling faster so there is more aerodynamic drag, reducing your fuel mileage. (Free)
4a) Those in REALLY cold places (Canada and parts of US where sub-freezing temps are common) often get a bra/cover to limit air intake and/or get a Frostheater. These will help the car warm up faster and therefore be more efficient. That said, don't start the car and let it idle to warm up--it won't warm much without load on the engine and you blow any mileage improvement from a warmer engine by the fuel lost idling (and it's bad for the environment).
5) Don't go oversize on tires or wheels. If you do get larger wheels make sure they weigh the same or less than stock. I run the ENKEI RPF1 wheels which weigh 13.5 lbs (16"). The cost isn't worth it for fuel savings, but I like how they look! 18" R32 wheels are around 27 lbs and will kill your economy.
6) Get a performance chip--Malone tunes as well as TDTuning & Rocketchip are all great choices. They will give you performance when you want it, and fuel economy when you drive nicely. My experience was that Malone gave me a bit more economy over RC. You'll be happy with any that's for sure! (~$300-550 depending on car)
7) Nozzles! ('96-03) Bosch nozzles (the genuine VW T4's are excellent, not to be confused with "DLC 1019's" which are not Bosch) ~($300)
8) Downpipe --- Breathes better, gave me ~2 MPG, but it helped. (~$250-400 again depending on model). On the common rail 2009+ cars, as long as you are an off roader only (or decide to run for testing purposes) you'll find a DPF delete (roughly $550) and stage 2 tune will average a 5-8 MPG improvement.
9) Larger turbo--again better breathing leads to better economy. Hybrid turbos appear to do the best for economy. ($850-3,000+)
10) Have fun, you can be frugal and finesse the car without being a worry wart. It's great to get your first 50 MPG tank, and amazing to get your first 60 MPG tank. Be honest with yourself and others, and realistic as well. When a member goes from a 38 MPG average and then reports a 72 MPG tank no one will believe them. My gains were from 38-42, 42-48, 48-54, a ton of tanks in the 53-58 range, and then a few breaking 60. My personal record is 62.48 MPG. Not bad, especially in an MK3. Probably won't happen in an MK5 or MK6 though!

*Following this guide won't guarantee the same results, but it will guarantee better results than what you have now. I reserve the right to change this guide at any time :).
Cheers, and happy TDI'ing!
-BB


***Cetane levels by fuel company. To ensure accuracy if you have a level to add to the list please forward an email from a corporate office to me, and I will add it to the list. Please bear in mind that the current minimum from refiners in North America is 40. Depending on the quality of the oil used as well as refining processes you'll find 40-42 from refiners in the US and Canada. Anything above that has to do with specific companies additive packages. When companies give a minimum value then it will be listed as a single number. When a company gives a range of numbers bear in mind that more often than not you'll probably find the lower number rather than the higher number. If 40 is listed then it generally means that fuel is bought as is from the refiner--if someone messes up and doesn't put in enough additive at the refinery then that can cause major problems for your fuel system. It's recommended therefore that if you get the inexpensive fuel with low cetane you use a cetane booster (PowerService, Lubromoly Cetane booster or Stanadyne are all great choices), or run a little biodiesel in the tank. If something higher than 42 is listed then the retailer adds their own additive package in addition to the standard refinery additive package. Generally speaking as long as 49 or higher is listed you do not need to worry about adding any additives yourself.

All California Diesel: Minimum 53 Cetane

Propel HPR, 75
Syndiesel, 60
BP (Amoco branded), 51;
Countrymark fuels Diesel-R, 50
Chevron, 49; or 51 with Techron D labels in select markets
ConocoPhillips through the 76 stations (California) 47-53
PetroCanada, 47-51
BP (Powerblend 47, otherwise 40-42)
Shell, 46;
Sinclair, 46;
Sunoco Gold, 45 (often +1-5) Sunoco regular is usually 40.
Exxon/Mobile, 43-46
Holiday Stations, 40-43
HESS, 40-42, can be up to 45.
Husky, 40 + diesel Max additives raise another 1-3 from there (41-45 max)
Pilot/Love's/Flying J/Valero/Sheetz/Walmart/Wawa: 40
for those in Washington State Cenex seems to have very high quality Diesel:
http://www.cenex.com/fuels/cenex-roadmaster-xl

I've been using it in our new 2015 Jetta S and the car just runs right!
the beave
 
Joined
Jul 4, 2015
Location
Kent Island
TDI
1996 VW Passat TDI
What kind of additives do People recommend for TDIs?

I have a 1996 Passat TDI 1.9
It has around 130k Miles, new timing belt, accessary belts, water pump, etc. I just revived Her from a 5 year slumber (non running, bought it from a Friend). It seems to run well, but doesn't want to rev much past 3500 RPM's.....
Could this be clogged injectors? Does anyone recommend "Seafoam" or some other additive to my car?

Tx
 

1998TDIMonster

Veteran Member
Joined
Apr 7, 2014
Location
Denton, Tx
TDI
1998 Jetta TDI 185k
I have a 1996 Passat TDI 1.9
It has around 130k Miles, new timing belt, accessary belts, water pump, etc. I just revived Her from a 5 year slumber (non running, bought it from a Friend). It seems to run well, but doesn't want to rev much past 3500 RPM's.....
Could this be clogged injectors? Does anyone recommend "Seafoam" or some other additive to my car?
Tx
Is it going into limp mode? Or can you feel the power throughout the power band? Was the timing verified using VCDS after everything was reinstalled? Clogged injectors could always be a possibility due to gunk getting in the I.P. after fueling and starting the car for the first time in many years. Not saying it is or isn't your problem in this case, but, if you plan on cleaning the injectors, i wouldnt use seafoam. I would use a bottle of diesel purge and make a setup where you bypass the fuel filter and run the car on the diesel purge only. It will not work nearly as well if you just dump it in the fuel tank. A quick search on the forum will reveal all the information you need to build yourself a setup to run the car on diesel purge.

I have used seafoam before and diesel purge. The seafoam (on a gasser) just smoked a lot. The diesel purge made the car run noticeably better. (Steering wheel used to vibrate from the rough diesel vibration. After the purge, idle smothed out so much that the steering wheel no longer vibrates.) if you want more scientific proof, my injector balance from group 13 went from +- 1.9 down to about +-.7. At 130k miles, it certainly will not hurt the car. Just remember, it is highly suggested you CHANGE YOUR OIL within about 1 week of doing the purge as it will deteriorate the oil. Love my 1.9l, lets just hope you dont mind getting your hands dirty! It is definitely a motor for people who are willing to do some of the work themselves! Good luck and let us know if you find anything else out.
 

xcmer

Active member
Joined
Jan 6, 2016
Location
Belchertown, MA
TDI
Jetta MK4
I've been following the tips here for a year or so and gotten tanks in the low 50s, but recently I've seen a bunch of advice of the perils of babying the engine such as liquid in the intercooler, soot buildup, and all that jazz. Is it an understood tradeoff, or is there a middle ground?
I'm hearing that going under 1800rpm is lugging the engine, and previously I was driving at 1500 most of the time, so...
 
Last edited:

mr_y82

Veteran Member
Joined
May 19, 2013
Location
Western NC
TDI
Used to have... '11 Golf, 6-spd, 2-door
MK4? Pretty sure there's no intercooler issue to worry about like the CJAA... I only let it go below 1750 or so when I am rolling downhill or slowing... seems like little to no benefit running the MK6 below that... not worth it in my opinion.

EDIT. Thanks deejaaa, for clearing that up (below)
 
Last edited:

deejaaa

Veteran Member
Joined
Apr 15, 2007
Location
Baytown, Texas
TDI
FOR SALE, 2002 Jetta GLS, 5 speed
he's talking about oil pooling in the IC. it's a known issue. revving it up between shifts should take care of it.
 

03arm

Member
Joined
Jun 13, 2016
Location
Saint Leonard, Maryland
TDI
2003 GLS
TDI Fuel Economy

Advisable - yes; depending on your driving destination. It would make a long trip quite tedious. I've practiced this with a gas engine as a pizza delivery driver & it makes a nice increase. Diesel is heavier than gas; so the practice makes more sense. Don't go below 1/4 tank however, to prevent crud in the bottom of the tank from getting into the fuel system. Hope this helps.

With due respect, I thank all of you for your tips. Its always a good learning process. Never forget - its a hobby.
Secondly, a simple question. Having less weight helps increase average. Would it be advisable to fill up only up to half tank and drive....rather than full tank. Condisering 7-8 gallons weight up to 60+ pounds.
thanks. Appreciate advise/constructive criticism.
 

KiwiCanuck

Well-known member
Joined
Nov 1, 2016
Location
Edmonton, Alberta
TDI
Oops.. driving a gasser
Hi, I'm new to TDI's & diesel cars. You seem vary knowledgeable, so I ask; what is a PD engine?
"very"

PD refers to the type of fuel injector. (I'll probably spell it wrong because I don't want to bother looking it up, but..) Pompe Duse (with the two dots (umlaut) over the "u").
There's a little solenoid-activated pump system in each of the injectors. It's more complicated than that, but professor Google can probably help more.
 

turbovan+tdi

Top Post Dawg
Joined
Mar 23, 2014
Location
Abbotsford, BC.
TDI
2003 TDI 2.0L ALH, auto, silver wagon, lowered, Colt stage 2 cam, ported head,205 injectors, 1756 turbo, Malone 2.0, 3" exhaust, 18" BBS RC GLI rims. 2004 blue GSW TDI, 5 speed, lowered, GLI BBS wheels painted black, Malone stage 2, Aerotur
he's talking about oil pooling in the IC. it's a known issue. revving it up between shifts should take care of it.
Driving it hard helps but if its that bad, he needs to drain it, otherwise runaway.
 
Last edited:

DPrlyG8

New member
Joined
Jan 22, 2017
Location
Florida
TDI
2012 Jetta Sportwagen
Would replacing my O2 sensor help with mileage?

I had an extremely intermittent CEL, something to do with the intake/MAF, don't remember the code, that would show up every couple of months. Replaced the MAF with a Bosch unit from http://metalmanparts.com/. My mileage went from mid 30s to low 40s, usually 41, 42. The CEL hasn't made a reappearance since, but now my cruise control won't maintain speed. Posts elsewhere suggest my O2 sensor may be bad. I am considering going ahead and replacing the O2 sensor. Any suggestions?

'04 Jetta TDI, manual trans, replaced cam and lifters, replaced IC, no mods
 

JohnWilder

Veteran Member
Joined
Jul 13, 2013
Location
Breckenridge, TX
TDI
2003 Jetta 5 spd manual
I have a 1996 Passat TDI 1.9
It has around 130k Miles, new timing belt, accessary belts, water pump, etc. I just revived Her from a 5 year slumber (non running, bought it from a Friend). It seems to run well, but doesn't want to rev much past 3500 RPM's.....
Could this be clogged injectors? Does anyone recommend "Seafoam" or some other additive to my car?
Tx
It could be low cetane. My ALH wouldn't rev above 3200 on one occasion. A new load of fuel seemed to correct this. I now put 1/4 oz. of non-additive 10w motor oil in the fuel. That seems to have corrected this problem. It also seems to have improved the fuel economy by about 1 mpg. You can get the oil at Tractor Supply.
 

JohnWilder

Veteran Member
Joined
Jul 13, 2013
Location
Breckenridge, TX
TDI
2003 Jetta 5 spd manual
I also have an 05 Passat wagon. Most of my driving is above 6,000' so less o2, less fuel, less power, better mileage. Was in Portland last month and mileage dropped into the 30's on the highway. Is that what you get with your 05 ? I do the driving techniques. Tried a cheap chip and got no improvement either 0-60 mph or mileage.
Any thoughts would be appreciated.
Rob
Driving at high altitude results in less drag so less power needed. I've noticed a measurable improvement at high altitude in mileage. However your engine will produce sea level power at 6000 ft. if necessary. It is turbocharged.
 

Tom Servo

Veteran Member
Joined
Jul 9, 2000
Location
LA (Lower Alabama)
TDI
2005 Gol TDI, blue and falling apart
Driving at high altitude results in less drag so less power needed. I've noticed a measurable improvement at high altitude in mileage. However your engine will produce sea level power at 6000 ft. if necessary. It is turbocharged.
Isn't that offset by the thinner air at height? I spent a short time in the Rockies and my mileage never seemed to creep past about 42 mpg, whereas "at home" in the deep south it was usually 45-49 mpg. The tank of fuel used going from Dallas to Arizona didn't even hit 39.
 

JohnWilder

Veteran Member
Joined
Jul 13, 2013
Location
Breckenridge, TX
TDI
2003 Jetta 5 spd manual
and p.s.
Has anyone found the way to time those dang stop signs? :mad: It seems like no matter how far back i start slowing, they are always red when i get to them. :D[/QUOTE]
I also live in Texas. I consider the designs of Texas roads to some of the worst I've seen. The parallel frontage roads on limited access highways is awful. I can't imagine who came up with such nonsense. I know they can time lights. How do I know? Because you will hit every red light no matter how you drive. Welcome to Texas! I believe it is deliberate to try to get you onto the toll roads. They make driving as aggravating as possible if you wish not to pay the toll.
 

JohnWilder

Veteran Member
Joined
Jul 13, 2013
Location
Breckenridge, TX
TDI
2003 Jetta 5 spd manual
I'm not 100% certain, but here is my theory: In the U.S., it is typically illegal to coast in neutral.

Although this law is probably intended to apply to manuals, the law probably doesn't specify.

As such, auto manufacturers are either legally required to sell auto-equipped cars which coast in gear, or face litigation every-time one gets into an accident.
These laws are from the old days of drum brakes that faded with excessive use. I've never heard of any such low being enforced in the last 30 years. Furthermore how would they know if you were coasting?
 

JohnWilder

Veteran Member
Joined
Jul 13, 2013
Location
Breckenridge, TX
TDI
2003 Jetta 5 spd manual
Isn't that offset by the thinner air at height? I spent a short time in the Rockies and my mileage never seemed to creep past about 42 mpg, whereas "at home" in the deep south it was usually 45-49 mpg. The tank of fuel used going from Dallas to Arizona didn't even hit 39.
My point is that drag is lower at any given speed at altitude due to the lower density of the air. If there is less drag then less power is required to move the car at any given speed. Why your mileage changes I don't know. I do know if you drive is a way to minimize the use of your brakes you will notice higher fuel economy. Remember every btu of heat generated in the brakes originally came from the fuel that did not move the car.
 

New Mickey

The user formerly known as mickey
Joined
Jun 6, 2017
Location
Utah
TDI
2015 Passat
Isn't that offset by the thinner air at height? I spent a short time in the Rockies and my mileage never seemed to creep past about 42 mpg, whereas "at home" in the deep south it was usually 45-49 mpg. The tank of fuel used going from Dallas to Arizona didn't even hit 39.
A naturally aspirated engine loses power as altitude increases. Turbocharging can maintain sea level intake pressures up to a certain critical altitude. (Said to be 6000 feet in the case of the TDI.) Altitude has no effect on power up to the critical altitude, but the car IS moving through thinner air. It won't matter at slower speeds, but at freeway speeds it becomes a substantial issue.

So in town it won't matter, but on the freeway at high speeds it will. The higher the speed the greater the effect of aerodynamic drag....and it's not a linear relationship. Drag increases exponentially as speed increases. Very little difference between 25 and 30 mph, but BIG difference between 75 and 80 mph, for example.

-mickey
 

New Mickey

The user formerly known as mickey
Joined
Jun 6, 2017
Location
Utah
TDI
2015 Passat
re: "Coasting in neutral." There is no such law. If anything it has to do with the way transmissions work. If the clutch is engaged and the transmission is in neutral then the input shaft of the transmission is loping along at "idle" speed while the output is spinning furiously.

It's also true that you have somewhat less control in neutral. The car will accelerate downhill more quickly than if the transmission is engaged, and you don't have engine braking to help you if you need to slow down quickly. Stopping distances are increases somewhat.

-mickey
 

New Mickey

The user formerly known as mickey
Joined
Jun 6, 2017
Location
Utah
TDI
2015 Passat
So here's a little bit of a trick.

"Hypermiling" involves working with gravity rather than against it. Allow the car to accelerate downhill, and let the speed bleed off going uphill. It make a huge difference, but may get you SHOT in traffic.

But that mindset can help you save some fuel if you have a DSG. When going downhill with the cruise control set the transmission will shift down a notch to help you slow down. Bump the stick into Tiptronic mode and it'll stay in top gear. You'll gain a bit more speed, which pays off as you get back on the flat.

If conditions warrant you can practice more aggressive hypermiling. The ultimate goal would be to maintain a constant power output. Whatever would keep you moving at a given speed IF THE ROAD WERE FLAT. Hold that power, and let the hills do what they will. Slow down going uphill, and speed up going downhill.

Other than that, I guess it's a question of how you define "economy." Are you talking about fuel or money? There at a lot of little things you can do to maximize FUEL economy, but most of them cost more than they're worth. If saving MONEY is the goal concentrate on driving style, avoiding carrying unnecessary weight in the car, and keep the tires properly inflated. (Don't be tempted to overinflate them in the name of "fuel economy." Any fuel you save is more than offset by the tires you ruin.....and tires are made of OIL, mostly.)

-mickey
 

New Mickey

The user formerly known as mickey
Joined
Jun 6, 2017
Location
Utah
TDI
2015 Passat
Watch your A/C. If you must use it, run it in Recirculate mode. You're only cooling the already cool interior that way, rather than trying to solve global warming.

If the outside air temperature is acceptable switch off the A/C. Use a higher fan setting, or crack the windows. That'll cause a LOT less drag than running the A/C compressor.

A/C running on a hot day can make a couple MPGs difference with a tiny engine and a lightweight car. I never noticed any difference with my full-size 4x4 pickup because everything is relative, and the A/C's drag was lost in the overall "hauling around 5000 pounds of metal".

-mickey
 

Chitti

Veteran Member
Joined
Feb 21, 2007
Location
Collegeville, PA (now in Denver, CO)
TDI
2002 Jetta TDI 5M (Donated). Now, 2006 TDI DSG
2006 TDI mpg blues!

I recently donated my 2002 Jetta TDI w/283,000 miles manual transmission. The car ran great and recently went into limp mode once. Hence, I gave it away. Consistently got 48-50+ mpg on the HWY. Usually drive 65 MPH in a 55 zone, 72 MPH in a 65 zone, and 80 MPH in a 75 zone. AC usage depending on weather. I drove the car from Philly to Denver end of Sep 2016.

Have 2006 (05.5) TDI DSG now. Went to Philly in June and came back to Denver two weeks later. Best I got was 40.8 mpg!! :eek: Tire pressure at 36 psi. Clean air filter. No clogs. Fuel filter new. Timing belt new. One highway segment (80 MPH, AC on, cruise on) gave only 36 mpg. What else should I check into? SCarroll doesn't participate much in these forums. One experience with A....ee not positive. Is there any other guru in and around Denver?

I wish I hadn't parted with my 02 TDI!

Chitti
 
Last edited:

Lightflyer1

Top Post Dawg
Joined
Sep 13, 2005
Location
Round Rock, Texas
TDI
2015 Beetle tdi dsg
The 2006's Seemed to be sensitive to where the timing was set to. +/- a little each way seemed to make a big difference in economy. There was/is a thread here about this.
 

rotarykid

Top Post Dawg
Joined
Apr 27, 2003
Location
Piedmont of N.C. & the plains of Colorado
TDI
1997 Passat TDI White,99.5 Blue Jetta TDI
I recently donated my 2002 Jetta TDI w/283,000 miles manual transmission. The car ran great and recently went into limp mode once. Hence, I gave it away. Consistently got 48-50+ mpg on the HWY. Usually drive 65 MPH in a 55 zone, 72 MPH in a 65 zone, and 80 MPH in a 75 zone. AC usage depending on weather. I drove the car from Philly to Denver end of Sep 2016.

Have 2006 (05.5) TDI DSG now. Went to Philly in June and came back to Denver two weeks later. Best I got was 40.8 mpg!! :eek: Tire pressure at 36 psi. Clean air filter. No clogs. Fuel filter new. Timing belt new. One highway segment (80 MPH, AC on, cruise on) gave only 36 mpg. What else should I check into? SCarroll doesn't participate much in these forums. One experience with A....ee not positive. Is there any other guru in and around Denver?

I wish I hadn't parted with my 02 TDI!

Chitti
The PD engines are just not as fuel efficient as the the rotary type injection engine.

You can tweak the timing some on the PD engine and increase the fuel efficiency. But it will never be as fuel efficient as the ALH or 1Z engines. Using high gear and keeping speeds down are the primary ways to increase fuel efficiency on the PD engine.

Also using coasting techniques with use of N when possible will help. Your numbers are actually pretty good for a PD engine on a drive like that.

On alh engines going into safe mode like you described you likely had a clog intake or head which was causing an over pressure to appear to be over pressuring the boost going into the engine. This is a common issue on these cars.
 
Top