Newbies and Vets: Tips for better fuel economy!

dslgolfguy said:

Just bought the Golf, first tank 36mpg, what do I need to do to get closer to 40 or 45. Car has 205,000 on odometer. I drive about 50 miles round trip a day mostly highway miles. As far as I know the car is bone stock, runs great and rides like new. I did change the oil put in lubro moly 5w30. Looking for suggestions to increase mpg.

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1) Drop your top highway cruising speed, this is the single most important factor.

2) Read the VW leaflet linked just above

3) Read the rest of this thread

2006 TDI mpg is too low

Need some help. I own a 2003 TDI (5 speed) that consistently gets 45 mpg. Little lower in the winter (Iowa) and little more in the summer. I just bought a 2006 (5 speed) and the best tank has been 41. I drive 120 miles a day with most of that on the interstate running about 75 mph. The 2006 seems to have more accelaration. Previous owner is unknown so I do not know if it has been chipped. Anyway to find out if it has been chipped for accelaration? Also - any advice on chips for max economy?

Thanks

If I recall correctly, the 2006 weighs more, and has more emissions equipment (for example, here in the UK it'd have a DPF, whereas the earlier car would not). Hence the slightly lower MPG. If you drop your cruising speed from 75 to 65 you'll probably add 10mpg.

06 Jetta TDI

I recently bought as 2006 Jetta TDI - got a great deal on a one owner, serviced by-the-book car. New TB/WP, new belts/hoses on the outside, looks like brakes are all new (including rotors - I had thought that they were recently turned when I looked at them through the spokes, but when I had the car inspected, - brand new. Fresh oil change (dealer oil - I know, use Rotella T6 TDT...)

Car had 118K miles, I now have circa 122K. Will use the car for around town communting and meetings at first but it is destined to be my son's car when he startes college next year. Handles really well, and I have just taught him to drive stick - he also loves it.

On to the mileage. I have the tires right on 32 lbs all round, got about 52 on the highway driving it back from Atlanta to Maryland, I was surprised since I cruised fairly high - about 78-80 most of the time (BTW - the speedo is 3-4 mhp fast - the 78-80 was off of my Magellan, which I think is very accurate.)

Since then, I seem to be getting about 42-43 avg with a mix of commuting (DC Beltway - sometimes like highway driving and sometimes like the Safeway pkg lot...) and errands around town - stop light to stop light.

I am really pleased with the car and the mileage. Considering a ROcketChip tune - I think I understand that it will not hurt the Fuel economy unless you keep your foot in it. Have not had the cam inspected yet, no obvious flywheel noises...

Bottom line - great car, fun to drive, great mileage, very insurable, very reliable if you stay on top of the maintenance...

john

MikeMars said:

If you drop your cruising speed from 75 to 65 you'll probably add 10mpg.

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No way....if I just drop to highway speed to 65.....that will add about 150+ miles to my tank? Seriously? That would get me from 37mpg now, all the way to about 47mpg?

Chewi said:

No way....if I just drop to highway speed to 65.....that will add about 150+ miles to my tank? Seriously? That would get me from 37mpg now, all the way to about 47mpg?

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Sounds like a bit of stretch to me too, but dropping to 55mph should get 47mpg in your car.

Anything over 55mph and the mpg drop off exponentially.

Just got back from a trip to the other side of the state. Idaho is 75 on the interstate - so cruise was set at 79. 300 mile trip - 39 mpg...

Chewi said:

No way....if I just drop to highway speed to 65.....that will add about 150+ miles to my tank? Seriously? That would get me from 37mpg now, all the way to about 47mpg?

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As far as MPG is concerned, aero drag is the square of speed, so the drag at 75 is 33% higher than at 65 mph.

Of course aero drag isn't the only factor... (although it is the biggest one at speeds > 50-55 mph)

I'd suggest actually trying it. Drop your speed to 65 or whatever for a tank, and see how you get on. Generally speaking dropping speed is the easiest way to increase MPG by far (until you hit 55 or thereabouts). My suggestion of 10mpg was based on the forum's '120 rule'.


Also try experimenting with this MPG calculator:
EcoModder: MPG estimator

I don't know whether the numbers in it are correct for your vehicle (the CD, and frontal areas would be particularly important figures to get right, as well as the drivetrain efficiency, and average engine efficiency). But once you've played around with it for a while, you'll see why I suggest dropping your cruising speed.

Of course with any such calculator, there are a lot of caveats. For example, it only tells you the instantaneous fuel consumption, not the trip fuel consumption. Engine efficiency varies by engine temperature, load & rpm (you can find the figures for load vs. rpm on the BSFC chart), and the calculator doesn't model this (to get around this, you have to enter the engine efficiency for the estimated load). Also note that it assumes no wind. For aero drag, it is your air speed not your ground speed which is important. It also only models steady driving - city driving is not catered for. Nor are hills.

Is coasting out of gear bad for engine?

I frequently take my manual tran 2012 TDI Jetta wagon out of gear and coast on hills (unless I need engine to brake on long, steep hills), up to stop lights, etc. It definitely gives me better mileage because I can coast much farther out of gear than in gear. I've tried it both ways, and out of gear definitely saves fuel. I figure, you must use fuel to get the car moving, and if you can keep moving without using the accelerator, why not use the momentum? It's free at that point. Also, any time you brake (even using the engine as your brake), you are wasting fuel that you have already paid for. If you're coming up to a light so fast that you need to brake, you are throwing away that momentum that you had to buy at the fuel pump. Ditto for going down hills. You can't avoid paying to go up them, but the downhill ride (and sometimes partway up the next hill) is free.

Here's my question: I've been told that it is bad for the engine to coast out of gear because it throws the computer off--does it? The reasoning went that the rpm's are out of line with the detected speed, so the computer will eventually adjust the engine incorrectly and--I don't know what--gum it up? wear it out?

Anyway, if anyone actually knows the answer to this question, I'd like to find out. We coasted a lot in the past with older gas-fueled engines. But do the modern computer-regulated tdi's need to be in gear all the time?

PracticalSort said:

I frequently take my manual tran 2012 TDI Jetta wagon out of gear and coast on hills (unless I need engine to brake on long, steep hills), up to stop lights, etc. It definitely gives me better mileage because I can coast much farther out of gear than in gear. I've tried it both ways, and out of gear definitely saves fuel. I figure, you must use fuel to get the car moving, and if you can keep moving without using the accelerator, why not use the momentum? It's free at that point. Also, any time you brake (even using the engine as your brake), you are wasting fuel that you have already paid for. If you're coming up to a light so fast that you need to brake, you are throwing away that momentum that you had to buy at the fuel pump. Ditto for going down hills. You can't avoid paying to go up them, but the downhill ride (and sometimes partway up the next hill) is free.

Here's my question: I've been told that it is bad for the engine to coast out of gear because it throws the computer off--does it? The reasoning went that the rpm's are out of line with the detected speed, so the computer will eventually adjust the engine incorrectly and--I don't know what--gum it up? wear it out?

Anyway, if anyone actually knows the answer to this question, I'd like to find out. We coasted a lot in the past with older gas-fueled engines. But do the modern computer-regulated tdi's need to be in gear all the time?

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I have the same car, manual jetta tdi, 2012. I coast out of gear all the time on my commute. i have several big hills to climb. gotta pay to get up, but most of them are gradual enough downhills, that I can coast out of gear at or near the speed limit for about 3 miles. that is three miles, in idle, travelling between 68 and 55mph. sometimes I have to give it a boost of about 3 seconds of acceleration if I have wind in my face. Also, when I coast, I put it in neutral and let out the clutch. idea is to save undue wear on the throw out bearings on the clutch. does it matter? who knows but it is easy enough to do.

one of the hills is too steep to coast freely, then I coast in gear to help hold back the car and reduce how much I have to use the brakes. but if I can maintain speed limit while coasting out of gear, I do it. You might be suprised how many locations on your drive you can do that. I am not wanting to coast so that I fall below limit like a true pulse and glide as i like to get to my destination and not take too much extra time to save a little bit extra. on my last commute with some extra 30 miles of driving, I returned 52mpg on the trip meter. I haven't had to fill up yet, so I don't know what the tank full mpg will be yet.

MikeMars said:

I'd suggest actually trying it. Drop your speed to 65 or whatever for a tank, and see how you get on. Generally speaking dropping speed is the easiest way to increase MPG by far (until you hit 55 or thereabouts). My suggestion of 10mpg was based on the forum's '120 rule'.

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Going to give it a try, shouldn't mean much more than leaving 10 min earlier in the morning.

Also, I just checked the website for my tires. Says max psi is 51......tire place that put them on has them 32psi all around. I'm guessing getting the psi a bit higher might help a little bit as well. Any thoughts on how much higher to go?

No, your car does not need to be in gear all the time.

PracticalSort said:

Here's my question: I've been told that it is bad for the engine to coast out of gear because it throws the computer off--does it? The reasoning went that the rpm's are out of line with the detected speed, so the computer will eventually adjust the engine incorrectly and--I don't know what--gum it up? wear it out?

Anyway, if anyone actually knows the answer to this question, I'd like to find out. We coasted a lot in the past with older gas-fueled engines. But do the modern computer-regulated tdi's need to be in gear all the time?

Click to expand...

Chewi said:

Going to give it a try, shouldn't mean much more than leaving 10 min earlier in the morning.

Also, I just checked the website for my tires. Says max psi is 51......tire place that put them on has them 32psi all around. I'm guessing getting the psi a bit higher might help a little bit as well. Any thoughts on how much higher to go?

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I usually run tires 38-40 psi assuming it doesn't exceed the mfg's maximum rating and find it helps mileage at the expense of dampening some bumps.

...the newer the worst?

Hi everyone,

I owned a 1997 GTI TDI Golf overseas and it was consistent over 50 mpg...today i have a Jetta that is consistent on 45 mpg. Beside the weight of the car and less hp I think that restriction over the emissions is one of the factor that made the fuel consumption worse. Yes diesel engine are not producing so much particulate pm5 and pm10 but how much more fuel are we consuming? Wasn't it better off to let the engine evolution forget about the emissions?

Ps. One tip for fuel economy is to carefully choose e big truck that runs at your speed and stick ~60-80 yards behind...you can feel the draft and the engine basically runs w/out fuel. Downside is safety...and rocks in your windshield...carefull! (I only did it a few times when I was running on fumes to get to the closest diesel gas station)

Imissmygolfgti1997 said:

Wasn't it better off to let the engine evolution forget about the emissions?

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What you lose in mileage you gain in safety. Our cars now and bigger, heavier and more crash worthy than those of 10 or 20 years ago.

Considering that engine technology has kept evolving it's pretty good that mileage hasn't fallen further than it has. I remember the people with their tiny Honda CRXs and Geo Metros with over 50 mpg, but they were tin cans. Fun as heck, but still tin cans. Now we have the CR-Z hybrid and Smart cars and neither gets anywhere near 50 mpg anymore.

Lower mpgs in any diesel old or new today also have something to do with the fact that ULSD has less energy than HSD or LSD. I have almost 30 years of data to back up this statement.......And I have a lot of data points since 2006 in IDI's and TDI's that back this up, LSD tanks compared to ULSD. I went out of may way to always buy LSD until it became unavailable at the end of 2010.

rotarykid said:

Lower mpgs in any diesel old or new today also have something to do with the fact that ULSD has less energy than HSD or LSD. I have almost 30 years of data to back up this statement.......And I have a lot of data points since 2006 in IDI's and TDI's that back this up, LSD tanks compared to ULSD. I went out of may way to always buy LSD until it became unavailable at the end of 2010.

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Can you publish that data?

All of my data that I came up with comparing my MPG between LSD and ULSD resulted in no change.

My local diesel retailer had LSD right through the "end date" of diesel. I really wanted to believe that LSD would give me more MPG, but I couldn't substantiate that claim.

On the flip side, the newer TDI's don't get the same MPG as my old '98.

On a 89 Jetta D with HSD in the tank had little trouble achieving high 40s ( 48 to 50 ), I owned two of these new. My 91 Jetta D could do the same until the switch to LSD ( 500 ppm ). In the later years LSD dropped to 350-400 ppm which caused another hit in mpgs. In the last years of LSD 150-350 ppm was the average which caused another hit in mpgs.

I drove 1.5s, 1.6s, 2.0s, 2.4s IDI Ds, TDs, 1.9 & 2.0 TDIs and I have years of data showing a real difference in achievable mpgs with the change in ppm of sulfur content. I ran some of each in every one of these. On my TDIs when they started selling ULSD along with LSD I documented as much as a 10 mpg difference. It was shocking to the point I thought I must had messed up my calculation, I hadn't!!!!!!


In the 80s until the change to LSD nationally in 1992 3000-5000 ppm diesel had significantly more energy and mpgs showed it. HSD was still available for off road and marine use well into 00s, could legally use the stuff as an additive.

CARB LSD diesel showed up in some areas of S CAL in 1986, 350 ppm limit. CARB diesel VLSD dropped to 150 ppm in mid 90s with some ULSD sold in the LA area in the late 90s.

Look at the data on how much energy is contained in each offering and you will see the simple truth that HSD and higher sulfur content LSD gave more energy when consumed. Which translates into higher achievable mpgs........I have data going back to late 70s, I clock every tank. In pretty much every offering every sold with VW diesel power ever sold here. HSD gave higher mpgs, higher content LSD gave higher mpgs, lower content LSD and ULSD killed achievable mpgs.

There is a simple explanation for the loss in MPG, Imperial Gallons (UK) are bigger than US Gallon.
1 Imp. Gal = 1.2009 US Gal.
I used to drive a GTTDi 130 in UK, remapped (tuned) to about 167HP and could get around 60 MPG at around 80 MPH in 6th Gear.

Where can i purchase a Malone Chip for my 2005 Passat?

Can it be that easy or do you have to run endless tests to see what works for you over what works for another..? Does timing have anything to do with it or is that a myth..? Am I just pulling straws here thinking what's best really has no bearing..? Main use is commuting to and fro both city or highway.. Current no-hands-on-skills-on-this-brand serves no reality in doing own so the rest is left to the tech whom have yet to trust to keep OTR..? Some direction can help if I'm in the right forum to get that or not..?

Anyone know the Cetane rating for Marathon here in the upper SE/lower Midwest? It wasn't in the posted list, and I assumed it was the same as Chevron, but maybe I'm wrong. There are no Amoco/BP stations here in the KY/OH/WV tri-state area, so I'm loking for the next best thing. I split time between here and IN, where Country Mark is plentiful (and very good). Needless to say, Country Mark gets all my business there.

Boy this is a LONG thread, and the load times on the older pages is really SLOW..;-)

Anyway, I have a 2009 Jetta TDI Sedan with auto, just purchased with 97K on the Odometer. I read in this post somewhere that moving the auto to N when stopped is good for a decent MPG savings. Can someone confirm this? Is there any disadvantages to doing this? I.e. unusual wear and tear on the auto-trans?

This is my first diesel. Paid 12,500 for the car, which seems a bit much for such high mileage, but it is super clean and I couldn't find a better deal after many weeks searching.

BleachedBora said:

NOTE: If you have a 2009 Common rail diesel or later do not run additives in the tank!

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BB, why is this?

I have a 2011 Jetta TDI wagon with 2900 miles. Drove from NYC to Washington DC and averaged 45.5 mpg according to the trip computer. Tried to keep a very steady foot and did not exceed 60 mph. Then I gave up and hit 80 mph for a while and and my mileage dropped to 44.9. But it was loads of fun.

Mpg is important but fun is just as important as well. Especially when the wife is sleeping; those are the times to see how much you can have.

Anyway, my question is will I ever see the car hit the magic number of 50 mpg ever or not? Given the fact that the car has so many gizmos and gadgets to make the EPA and other regulatory agencies happy.

Your wi
fe doesn't have a wake-up alarm at 70 mph? What do you feed her? LOL

lsnover said:

Boy this is a LONG thread, and the load times on the older pages is really SLOW..;-)

Anyway, I have a 2009 Jetta TDI Sedan with auto, just purchased with 97K on the Odometer. I read in this post somewhere that moving the auto to N when stopped is good for a decent MPG savings. Can someone confirm this? Is there any disadvantages to doing this? I.e. unusual wear and tear on the auto-trans?

This is my first diesel. Paid 12,500 for the car, which seems a bit much for such high mileage, but it is super clean and I couldn't find a better deal after many weeks searching.

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You have a DSG transmission. I does NOT have a torque converter, so you should leave it in drive while sitting at a light.

Always use your parking brake when you park this car. It can roll 8 inches or so while in park.

Parking (not waiting at light....)

Stop car with foot brake.
Apply park brake.
Put shifter into park position.
Turn off car.
Remove key.
Exit and lock car.

Starting car.

Insert key into ignition.
Turn key to run position.
Wait for glow plug light to go out.
Apply foot brake.
Start engine.
Move shifter to either R or D.
Release park brake.
Drive away.

The transmission requires expensive service every 40,000 miles.
The engine requires a Timing Belt change some time soon. Check your maintenance schedule and find a trusted mechanic (see tdi101 forum) to do the work instead of the dealer.

Bill

nickeasy said:

BB, why is this?

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I wish I knew - I only know that VW had a TSB go out saying that adding a fuel additive was grounds to deny warranty claims on the fuel system. With the issues with the HPFP I'd maintain a no additive policy if I owned one!

Run a high cetane fuel (listed on first post) and you'll be golden.

-BB

PS RE: the tunes - we do carry Malone tunes

BleachedBora said:

<SNIP>I only know that VW had a TSB go out saying that adding a fuel additive was grounds to deny warranty claims on the fuel system. <SNIP>

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Link(s)? Documentation? What year(s)? What engine(s)? What car(s)?

Anything at all?

I have heard of dealers (not VWoA) trying to weasel, but NOT any TSBs about fuel additives.

Thanks,

Bill

Bill, thanks.

I tried putting the car in Neutral at a few lights and could not feel any difference. FYI, I'm more used to Manuals then autos, so I ALWAYS put on the Emergency brake before putting my cars in neutral with my foot on the brake. This is a good idea in ANY car really, but many folks with autos seem to ignore this good practice.

I've also tried putting into N while going down long hills. It seems to help a bit, based on the trip computer, but I'm not sure it's a good idea on automatics.

40X40 said:

You have a DSG transmission. I does NOT have a torque converter, so you should leave it in drive while sitting at a light.

Always use your parking brake when you park this car. It can roll 8 inches or so while in park.

Parking (not waiting at light....)

Stop car with foot brake.
Apply park brake.
Put shifter into park position.
Turn off car.
Remove key.
Exit and lock car.

Starting car.

Insert key into ignition.
Turn key to run position.
Wait for glow plug light to go out.
Apply foot brake.
Start engine.
Move shifter to either R or D.
Release park brake.
Drive away.

The transmission requires expensive service every 40,000 miles.
The engine requires a Timing Belt change some time soon. Check your maintenance schedule and find a trusted mechanic (see tdi101 forum) to do the work instead of the dealer.

Bill

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