Newbies and Vets: Tips for better fuel economy!

Just do the "free" stuff: max psi in tires, when you replace your tires go with a low rolling resistant type; ex. Goodyear Assurance-Fuel Max, don't go over stock width: wider tires=more resistance, in the winter-block off part of your grill to help your engine stay warm, use a block heater if necessary, coast in gear, drive 52-62 mph, get into 5th as soon as practical. Raising cetane helped me, especially in the winter. Ventectomy and driving slower will get you into the 800 mile club.
Resist the temptation to buy anything extra, even a scangauge. How much fuel can you buy with that $170 device? What kind of mileage increase do you have to realize to pay for it? Same goes for all the other gadgets. If economy is your goal-economize!!

roadhard1960 said:

If you can go down that decline with your foot off the throttle, the engine is receiving no fuel. When in neutral it is using fuel. This assumes the engine is running faster than about 1,000 rpms when in gear.

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The car would roll longer out of gear than in gear. So pulsing and then gliding in neutral will give you better gas mileage than pulsing and gliding in gear even though the injectors shut off when you are gliding in gear. The longer glide in neutral saves more fuel than gliding in gear. YMMV.

nj1266 said:

The car would roll longer out of gear than in gear. So pulsing and then gliding in neutral will give you better gas mileage than pulsing and gliding in gear even though the injectors shut off when you are gliding in gear. The longer glide in neutral saves more fuel than gliding in gear. YMMV.

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The final fuel saving results depend on many factors.

Length of hill
Speed of car
Traffic
Future intentions (at bottom of hill, stop or turn or climb even bigger hill, etc.)

Sometimes you should be in gear and sometimes perhaps not. If the hills are particularly steep and long it can be deadly to coast out of gear. (Any halfwit with internet access can read your advice decades from now and act on it... hmmm.)

This has been beaten to death many times before you became a member. Please refer to past posts and threads.

Bill

red928 said:

Just do the "free" stuff: max psi in tires, when you replace your tires go with a low rolling resistant type; ex. Goodyear Assurance-Fuel Max, don't go over stock width: wider tires=more resistance, in the winter-block off part of your grill to help your engine stay warm, use a block heater if necessary, coast in gear, drive 52-62 mph, get into 5th as soon as practical. Raising cetane helped me, especially in the winter. Ventectomy and driving slower will get you into the 800 mile club.
Resist the temptation to buy anything extra, even a scangauge. How much fuel can you buy with that $170 device? What kind of mileage increase do you have to realize to pay for it? Same goes for all the other gadgets. If economy is your goal-economize!!

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$170 =65 gallons of D2 @ $2.60/gallon. (current local price) That is 2600 miles @ 40 MPG, a tiny distance... when compared to the expected life of the car.

I think most people can realize from 2 to 10% increase in fuel economy if they have a tool (SGII or similar) that can report and record actual fuel economy. Like all tools, the user must understand how to use it and then ACTUALLY put it to best use. I clear trouble codes on non-VWs for friends as a courtesy with mine.
It makes economic sense to buy a Bentley Manual too, but only if you intend to read and use the info it contains.

Bottom line, economy may be what we tell people why we own these cars, but we really drive them because we like them.....

Bill

A scangauge easily pays for itself.

Lets keep the math simple, I was able to save one full liter per 100km using the ScanGaugeII. I went from 5.7L/100km to 4.7L/100km (17% better fuel economy?). At $1 per liter I only had to drive 17,000 km before the device paid for itself.

Also, if I continue to use the Scangauge to get 4.7L/100km I can pocket an extra $160 at every oil change interval of 16,000km.

Its also an extremely useful diagnostic tool. I really impressed my wife's grandfather when I diagnosed his unplugged O2 sensor without having to go back to the shop that had just replaced it. I also impressed my dad when I diagnosed that his gas cap was not tight and saved him a trip.

You can also use it to monitor your MAF and MAP sensors.

My favorite game to play is to watch the "km to Empty" and shoot for more than 1000km per tank from the very first km driven away after filling up.

Also if you think about it you pay more than $ 17,000 for a vehicle, why not add a $170 option (less than 1 percent of the purchase price, far less than the tax you pay) an option that will save you MINIMUM 2% in fuel and up to 20% in fuel?

At 5.7L/100km that is .057L/km at $1/L your cost $0.057 per km. If you drive your vehicle for 300,000km (that is why you bought the diesel, right?) it will cost $17,100 for fuel. If you save $20 you get $3420 back. But even if you only save the minimum 2% you get $342 which means you doubled your investment of $170 for the Scangauge.

Some might argue that they use a pencil and paper to keep track of fuel economy and do not need a fancy device. These people have never used a properly configured Scangauge.

Pulse and glide not applicable for diesels?

I don't believe that pulse and glide is applicable for diesels. It was developed by people trying to get maximum mpg using gasoline engines to overcome the tremendous energy losses gas engines have controlling the power output using a throttle valve at the air intake. It takes a lot of power to pump air across a partially closed throttle valve. A 300 HP car driving at 60 mph only needs about 30 HP, and can actually use more power (fuel) to suck air into the engine than it uses to move the car. Gas engines have lousy efficiency when running with the throttle valve only partially open. This is called the pumping loss. (http://en.wikipedia.org/wiki/Engine_efficiency) However, their efficiency is very high if their throttle valve is wide open. Problem is that they go too fast then.

Solution? Pulse and glide! Open the throttle valve wide for a short time, accelerating efficiently up to some low speed, put it in neutral, turn off the engine and coast to a low velocity, and then turn on the engine to do that again, and again and again, etc. They can get well over 100 mpg that way.

Diesels don't have a throttle valve in the air intake. Their power is controlled by changing the amount of fuel squirted into the engine. They don't have the big pumping loss. Pressing the accelerator to the floor squirts the maximum amount possible fuel into the engine, causes black smoke and thus less efficiency.

Getting maximum mpg with any vehicle involves driving in such a way that you use as little energy (fuel) as possible to move the vehicle (overcoming friction). For diesels, that means high tire pressure to reduce rolling friction, low speed to reduce aerodynamic drag, minimum braking to avoid converting speed into friction, optimum engine speed (approximately 1800 RPM) to get best specific fuel consumption (lb/hour fuel per horsepower), etc. Coasting down hills with the transmission in neutral will help as long as you don't get going too fast. Coasting in gear transfers car momentum into engine friction and is not good, even though your SG II says you're getting 9999 mpg! Minimize energy going into friction. I don't think pulse and glide is for diesels.

Read through the thread and never saw where anyone knew what Murphy Oil/Walmart cetane ratings were so I emailed Murphy Oil and this was their response:

Hi Ben -

I am told that it varies based on supplier, product, and time of year, but normally is around the 45 to 50 Cetane range. I hope that helps.
Thanks,

Emily
Murphy USA

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vwjettadsl said:

Read through the thread and never saw where anyone knew what Murphy Oil/Walmart cetane ratings were so I emailed Murphy Oil and this was their response:

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Thanks for adding to the knowledge base. Indeed for "non brand" branded WalMart "house brand," this range of cetane ratings is one of the highest. If the WalMart house brand fuel is priced lower than the branded D2's, it is indeed a winner. It is really too bad the majority of "out west" WalMarts do not carry D2 fuel let alone RUG to PUG.

I've been doing some searches on ventectomies since a lot of people seem to recommend it. Basically it just allows you to put more diesel into the tank right? Is this still a viable mod for a 2010 tdi? Every thread i've found here and elsewhere all seem to be for older models.

archetypaul said:

I've been doing some searches on ventectomies since a lot of people seem to recommend it. Basically it just allows you to put more diesel into the tank right? Is this still a viable mod for a 2010 tdi? Every thread i've found here and elsewhere all seem to be for older models.

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Sorry, but since the MKV came out the ventectomie has not been possible. (It is already done for you)


Bill

40X40 said:

Sorry, but since the MKV came out the ventectomie has not been possible. (It is already done for you)


Bill

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Can you actually fill one of the new models up to the brim like the button/ventectomy allows on older models?

Tom Servo said:

Can you actually fill one of the new models up to the brim like the button/ventectomy allows on older models?

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Yes, easily. Fill the tank normally until auto shutoff, then fill the rest of the way as slow as it takes to keep the foam under control. It is quick and easy as ULSD foams much less than the old LSD used to.

Bill

OK, Newbie here...got my jetta TDI (automatic trans) a month ago and love it, can't see myself buying another gas vehicle. I am getting 43+mpg/tank so far but am still learning the car. Question, does it harm the tranny to shift into neutral, coasting, and then gently shift back into drive? I am able to do this alot while driving my daily comute.
Great web site!

Leave the car in drive. For safety reasons. If you want more miles per gallon. Check out the rest of this thread.

i sometimes shift into neutral while in traffic and i'm on the downslope of the highway. in traffic coasting at around 10mph the car has such incredible engine braking that i'm almost coming to a stop. i simply shift it into neutral so i can coast all the way down without having to juice it up to move another 10 feet.

Duh !

'nother newbie. What is "venting" ?

Stamie said:

'nother newbie. What is "venting" ?

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The search box is your friend. Alternate names: "vent trick", "ventectomy", "remove the vent guts". Also see the TDIFAQ (at the top to the right of "Forums"), section 2: General FAQ.

--5/25/10
Driver: moonranch
Miles: 1006.7
Gallons: 15.776
Model Year: 2001
Model: Golf
Tranny: 5M
Fuel Type: ULSD
--63.8mpg Mostly commute

Thanks Mike, Is that a skunk? Panda?

Stamie said:

Thanks Mike, Is that a skunk? Panda?

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No, silly, it's a badger.

Silly me !

red928 said:

Just do the "free" stuff: max psi in tires, when you replace your tires go with a low rolling resistant type; ex. Goodyear Assurance-Fuel Max, don't go over stock width: wider tires=more resistance, in the winter-block off part of your grill to help your engine stay warm, use a block heater if necessary, coast in gear,

Click to expand...

Read a lot of the thread but did not see any numbers for the Goodyear Assurance-Fuel Max tires. Anyone have real world results?

drive 52-62 mph,

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Is that an aveerage to shoot for? Or on road speed? Is it worth it?

I just finished two 860 mile interstate trips, one "loaded down" with books and stuff (maybe 400 lbs) and 2 passengers, another 400 lbs., the return with just a little more than the passengers. 143 hours down, 14 hours and 10 minutes back. Thus I "averaged" 61.5 mph. But that included fuel/pit stops. Most of the time the speedometer was between 70 to 80, following the flow of traffic. Mileage was 39.6 per MFD. Or about 22 gallons each way.
If I had dropped my speed to 55 it probably would have taken several more hours (also would have needed more breaks). Did not seem cost effective.

Resist the temptation to buy anything extra, even a scangauge. How much fuel can you buy with that $170 device? What kind of mileage increase do you have to realize to pay for it? Same goes for all the other gadgets. If economy is your goal-economize!!

Click to expand...

Agree - don't buy it for the economy/fuel savings. But I'm telling my wife the Revotechnik Performance Software (stage 1) may improve mileage

newbury said:

Read a lot of the thread but did not see any numbers for the Goodyear Assurance-Fuel Max tires. Anyone have real world results?

Is that an aveerage to shoot for? Or on road speed? Is it worth it?

I just finished two 860 mile interstate trips, one "loaded down" with books and stuff (maybe 400 lbs) and 2 passengers, another 400 lbs., the return with just a little more than the passengers. 143 hours down, 14 hours and 10 minutes back. Thus I "averaged" 61.5 mph. But that included fuel/pit stops. Most of the time the speedometer was between 70 to 80, following the flow of traffic. Mileage was 39.6 per MFD. Or about 22 gallons each way.
If I had dropped my speed to 55 it probably would have taken several more hours (also would have needed more breaks). Did not seem cost effective.

Agree - don't buy it for the economy/fuel savings. But I'm telling my wife the Revotechnik Performance Software (stage 1) may improve mileage

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The cleanest way to shoot for is road speeds (and probably just as important the time it took to travel that distance. The average speeds as you allude are easily left to GPS, MDF, (again if you have them) etc.

Purely as other data points, on trips (such as you have described) (DSG), I have kept it under 90 mpg and posted 43/44 mpg.

On a Mk IV 5 speed manual due to GREAT customer services (highway patrol 5 car wolf packs going in either direction with a stationary "radar shooter") across 3 states, keeping it @ 75 mph with bursts to 80/85 it posted 59 mpg. Normally I am ok with 48 mpg, 584 miles in 6.25 hours, 12.1 gals.

Does anyone wear an ice vest on this forum when it gets blitzing hot? If so where did you get yours? Approxiamate price?

Hell Yeah !!! Don't you ?

Ton said:

Does anyone wear an ice vest on this forum when it gets blitzing hot?

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LOL...it'd last about 5 minutes here.

Is shifting to neutral OK in an automatic?

The volume of information in these forums can be daunting! I'm driving my first TDI for a couple of weeks now - A 2005 Passatt. I don't know what code that is...
The computer is estimating that I get ~ 45 mpg, but I'll be double checking each time I fill up and will report on the mileage page.
Question: The Passatt is an automatic (not my preference). Is there any advantage/disadvantage to shifting into neutral to coast down some hills on country roads? Am I impacting the transmission?

no doubt it's here - somewhere - I search and see all kinds of takes on fuel efficiency(I've read all 30 pages!). Please excuse this very simple question: how to best accelerate with a TDI/DSG. What's the consensus? Do you get up to speed quickly, be it 35, 40, 50 then ease back?
I find myself accelerating more slowly, climbing to desired speed - so almost teasing the gas peddle: an easy press/release, press/release. It seems to come out of the low, 8 - 10 - 12 mpg read quicker that way. thanks for you patience with a newbie.

FUZ and plap - welcome to the club!
Keep the car in gear, the ECU cuts fuel when you don't have your foot on the accelerator, which means you're using no fuel at all when you're going down the hill.

Accelerate slowly, you'll use a lot less fuel then if you jackrabbit up to speed. When I was doing my 60 MPG tanks with my MK3 I would watch my boost gauge and make sure to use 3-4 lbs of boost on acceleration. This translated to a very slow acceleration, but it also helped with mileage significantly.

I've been getting 50-53 with a 50/50 mix of city/highway lately on my '01 Golf. My last tank was 39.5 a couple days ago. Part of it was I had to fuel at a different location with questionable quality fuel when I was in the middle of nowhere, and part of it was I had a bit more fun on the tank, and finally my tires were at 32. I've bumped them back up to 40 and gone back to my usual place. Hopefully I'll be back over 50 the next few tanks.

Also bear in mind the MK3 and the MK4 are both much lighter cars than the Passat and the MK5. Because of that we'll always get better mileage than you can ever expect, but you can still do a lot of things to maximize your mileage.

-BB

Besides accelerating slowly, shift points (in a manual) are important, too. A lot of people seem to believe you should shift as soon as you can without lugging the engine. I'm not sure driving that conservatively is a good idea for the turbo, 100% of the time, but you definitely don't wanna creep up in speed while staying in the same gear.