Disappointing mpg from 2.0 TDI

buyingconstant7 · Jul 16, 2014

I bought this car end of 2012 and now have roughly 37,000 miles on it. The mpg has been consistent at 38-40mpg. Trouble is, my trips are at 65mph for 45 mins on a flat highway at warm temperatures with A/C rarely on and windows always up. And I always get roughly 39 mpg. My average speed on my tanks has been about 57mph. I drive with economy in mind and don't drive hard at all. My tires are about at 39PSI each and are worn well with rotations done religiously. Also, services are never missed and I don't carry heavy things or passengers. Why can't I break the 42mpg VW says I can? I know other people hit 50+ in their 2.0 and 1.9 TDI's. What gives?

geodug · Jul 16, 2014

Lots of things influence fuel efficiency. Is your car DSG or 6MT? What size are your wheels and tires? What is your driving style? Bump your air pressure up a bit.

Practice your 3 don'ts. Don't touch the throttle more than you have to. Don't touch the brakes more than you have to. Don't move the steering wheel more than you have to.

A lot of people don't understand the steering wheel tip but some people turn a corner like they are sawing wood. We don't like to think we do that but truth be told we can all concentrate and get around corners much cleaner than we do.

rotarykid · Jul 17, 2014

Need some details, manual or automatic? As said wheels and tires???

Peddle pushers in DSG cars can struggle to get above the high 30s....

A pebble pusher is someone that just gets behind the wheel, puts it in D then never give driving another thought just pushing the pebbles without a thought to the terrain you are driving over, driving conditions, speeds in relation to traffic around them, and they use the brake pebble a lot......

Everytime you accelerate just to have to hit the brakes a few seconds later you are wasting fuel! Only accelerate when you know you can use that energy to keep moving for at a while.

It comes down to depending on conditions driven in and how much you are involved in driving as to what you will see.....

The more involved you are in paying attention to driving you are the better your mpgs will always be. Things like what gear is correct for the conditions you face or if it would be better to be in N the higher your mpgs will always be....Can the terrain can be used as fuel to hold speed or to accelerate saving fuel...... Could a short burst of energy be used to get going then shifting in N to use a down hill to get the rest of the way up to the desired speed.... Or can a shorter distance traveled staying in gear than if you were in N without throttle {fuel} being required....

The drivers that always see the highest mpgs are ones that rarely use the brakes. They use the transmission( shifting down using lower gears to reduce speed putting the engine in overun to slow ) and do a lot of rolling in N when conditions warrant it. This is part of normal driving in a manual trans car but takes a little effort to do in a automatic but saves fuel in both.....

Lightflyer1 · Jul 17, 2014

Your expectations are wrong. Look at fuelly.

https://www.fuelly.com/car/volkswagen/jetta?engineconfig_id=6767&bodystyleconfig_id=2&submodel_id=

Most are right where you are. Very few drivers actually get 50+ and those that do have to work at it or drive constant steady state conditions.

thebigarniedog · Jul 17, 2014

Lightflyer1 said:
Your expectations are wrong. Look at fuelly.

https://www.fuelly.com/car/volkswagen/jetta?engineconfig_id=6767&bodystyleconfig_id=2&submodel_id=

Most are right where you are. Very few drivers actually get 50+ and those that do have to work at it or drive constant steady state conditions.

Exactly. I would add ".... and those that do have to work at it, drive constant steady state conditions or simply lie about what their real fuel mileage per gallon actually is".

Cincy_TDI · Jul 17, 2014

I have about 28k on my 2013 Passat dsg, best I have gotten is 59.3 mpg and usually average 40-50 on highway. I split some days highway and city. When that happens I hit the 30-40. I always use AC, and ways drive 65-70. Last long trip Cincinnati to Florida going down was 49, coming home was 47. Average speed 75.

Maybe your driving to slow, or dragging a brake.

VarmintSlayer · Jul 17, 2014

I used to get mid to high 30's. Rural roads 50 minutes to work.

Now I'm seeing mid 40's. Mostly all highway 3 hours to work.

skramer · Jul 17, 2014

thebigarniedog said:
Exactly. I would add ".... and those that do have to work at it, drive constant steady state conditions or simply lie about what their real fuel mileage per gallon actually is".

And have removed all emissions systems

Ramairetransam · Jul 17, 2014

going 65 the whole way home from work yesterday i got 46 mpgs .

Are you up to date with oil change , filters and such .

skramer · Jul 17, 2014

Ramairetransam said:
going 65 the whole way home from work yesterday i got 46 mpgs .

Are you up to date with oil change , filters and such .

You are using your dream meter right? My dream meter is over 10% high vs calculations with fuelly. When you subtract the estimated over estimations by your computer, that puts it down to low 40's which is the range we are talking about

SkeeterMark · Jul 17, 2014

I dunno. The OP's drive seems perfect to exceed 40mpg regularly. And he seems to be actually employing a driving style that would yield better fuel economy.

I don't really drive for mileage, sans a few tanks here and there where I tried to get max mpg. I think I've only had 3 tanks under 40 mpg.

If I didn't have to deal with winters, my lifetime fuelly numbers would be dang close to 50.

USCGTO · Jul 17, 2014

I was calculating some random numbers and realized one fact.

The Tank size is fixed for all of us - 18.5 gallon.

So assuming we run the tank dry, all those people claiming to hit 700 miles plus are basically averaging 37.83 mpg if they run it dry or assuming they used 18 gallons ` 38.88 mpg.

And the ones in the 800 club are averaging 43.24 - 44.44 by the same yardstick.

The dream meter is a lying son-of-a-*****.

USCGTO · Jul 17, 2014

I averaged 40.88 for my first ever tank.

I could have done well. But some effort was lost in sitting in traffic and breakin-in the engine

TDI_Bug_52mpg · Jul 17, 2014

The big four-
1) Tire pressure
2) Air "filter"
3) Coasting
4) Tranny fluid (if a manual)

SkeeterMark · Jul 17, 2014

USCGTO said:
I was calculating some random numbers and realized one fact.

The Tank size is fixed for all of us - 18.5 gallon.

So assuming we run the tank dry, all those people claiming to hit 700 miles plus are basically averaging 37.83 mpg if they run it dry or assuming they used 18 gallons ` 38.88 mpg.

And the ones in the 800 club are averaging 43.24 - 44.44 by the same yardstick.

The dream meter is a lying son-of-a-*****.

My tank is 14.5 gallons. I get over 700 miles quite often, without running it dry. All my numbers are calculated. The MFD in my vehicle is about 4.6% optimistic over the life of my car.

IndigoBlueWagon · Jul 17, 2014

I think the OP's FE is lower than it should be. I've averaged 43.5 on my '12 Golf since new, typically drive 75-80 on the highway, lots of local use, frequently shift at 3K RPM plus, spend a fair amount of time in traffic. I saw 47.8 on a trip back from Michigan after the '12 Fest, running at 80 MPH, A/C on. That was a 700 mile tank.

I'd expect the OP should get mid-40s instead of the 39 he's seeing, unless there's something odd about his drive (high winds, maybe) that is bringing FE down.

SkeeterMark · Jul 17, 2014

TDI_Bug_52mpg said:
The big four-
1) Tire pressure
2) Air "filter"
3) Coasting
4) Tranny fluid (if a manual)

The bigger three
1) Head wind
2) Incline
3) Cold ambient temperatures

Ironman11142 · Jul 17, 2014

numbers seem low

I average 42 mpg with 50/50 highway/city driving..... If I have extra highway miles, my average has bumped up to 45 mpg on a tank....
I always use AC but, my tire pressure is low (30 psi) due to being serviced at 30k mile service at stealership (last free service)....
My tires have nitrogen fill (came that way)....will adding regular air to it to bring air pressure up make much of a difference?
thinking of bumping pressure to 35 psi....thoughts?
I do some coasting in gear/neutral on exit ramps....drive speed limits.
thanks,

LarBear · Jul 17, 2014

Quote:
My tires have nitrogen fill (came that way)....will adding regular air to it to bring air pressure up make much of a difference?
thinking of bumping pressure to 35 psi....thoughts?

Air is ~78+% nitrogen, and the only advantage in filling tires with nitrogen that I can think of is that it's dry while most compressed air has a trace of water in it which can corrode some tire pressure sensors. I run the tires on the Jetta at 35-36 psi and if they're lower fire up the compressor and add air. Nitrogen isn't magic regardless of what some shops tell you.

On the few road trips we've taken the Jetta gets over 40 mpg calculated using cruise control set at the speed limit (which is 70-75 mph), up and down hills and mountains. Don't do anything special, and round trip to Northern UT (~1100 miles) last fall we averaged over 45 mpg hand calculated.

VeeDubTDI · Jul 17, 2014

Cincy_TDI said:
I have about 28k on my 2013 Passat dsg, best I have gotten is 59.3 mpg and usually average 40-50 on highway. I split some days highway and city. When that happens I hit the 30-40. I always use AC, and ways drive 65-70. Last long trip Cincinnati to Florida going down was 49, coming home was 47. Average speed 75.

Maybe your driving to slow, or dragging a brake.

The Passat is a totally different beast and isn't really an apples to apples comparison with the Jetta.

Cincy_TDI · Jul 17, 2014

True and that is my fault for posting. But if the user is getting very low MPG we both have TDIs as I understand, using as an example is why I added my 2% of a buck...

TDIMeister · Jul 17, 2014

It is a mystery to me how people can do acrobatic arithmetic determining MPG when in Canad nothing in the car reports distances in miles and fuel is not dispensed in gallons. And I consider myself decent at math.

geodug · Jul 17, 2014

TDIMeister said:
It is a mystery to me how people can do acrobatic arithmetic determining MPG when in Canad nothing in the car reports distances in miles and fuel is not dispensed in gallons. And I consider myself decent at math.

In my case I am old school and get confused with L/100 km. Maybe the OP is like me and set their MFD to US standard.

Mike_04GolfTDI · Jul 17, 2014

I remember reading something about the TDI engine being most efficient between about 2000 and 3000 RPM at full throttle.

It takes X amount of fuel just to overcome the internal friction of the engine, and if you're accelerating very slowly all the time, your percentage of fuel that is actually moving the car vs just turning the engine is not as high as it could be.

So, try getting up to speed fairly briskly, as opposed to gently accelerating like people in SUV's do nowadays (haha).

After reading that, I tried it, and I think my mileage went up a bit. However, the thing is so efficient that I don't really think about it too much. I just drive however I want, and my overall average is 42 mpg.

I'll see if I can dig up the explanation that I read about this....

EDIT: So I dug around a bit and found lots of threads discussing this, but not the specific one I was thinking of. Anyway, it would seem that there is some belief that hard acceleration without revving too high will yield better efficiency because you're taking advantage of the characteristics of the Diesel engine...or whatever. Try it and see what happens.

VarmintSlayer · Jul 18, 2014

TDIMeister said:
It is a mystery to me how people can do acrobatic arithmetic determining MPG when in Canad nothing in the car reports distances in miles and fuel is not dispensed in gallons. And I consider myself decent at math.

I just use the unit conversion chart at the top of the page.

I took grade 12 math twice.

buyingconstant7 · Jul 18, 2014

rotarykid said:
Need some details, manual or automatic? As said wheels and tires???
Peddle pushers in DSG cars can struggle to get above the high 30s....
A pebble pusher is someone that just gets behind the wheel, puts it in D then never give driving another thought just pushing the pebbles without a thought to the terrain you are driving over, driving conditions, speeds in relation to traffic around them, and they use the brake pebble a lot......
Everytime you accelerate just to have to hit the brakes a few seconds later you are wasting fuel! Only accelerate when you know you can use that energy to keep moving for at a while.
It comes down to depending on conditions driven in and how much you are involved in driving as to what you will see.....
The more involved you are in paying attention to driving you are the better your mpgs will always be. Things like what gear is correct for the conditions you face or if it would be better to be in N the higher your mpgs will always be....Can the terrain can be used as fuel to hold speed or to accelerate saving fuel...... Could a short burst of energy be used to get going then shifting in N to use a down hill to get the rest of the way up to the desired speed.... Or can a shorter distance traveled staying in gear than if you were in N without throttle {fuel} being required....
The drivers that always see the highest mpgs are ones that rarely use the brakes. They use the transmission( shifting down using lower gears to reduce speed putting the engine in overun to slow ) and do a lot of rolling in N when conditions warrant it. This is part of normal driving in a manual trans car but takes a little effort to do in a automatic but saves fuel in both.....

Shes a dsg. I definitely pay attention. I know for a fact that I drive the most economically as possible. I coast, I match traffic speeds and also drag behind semi trucks. I still can't break 41

maxst2 · Jul 18, 2014

I have a 2014 3300 on the clock. I have been getting 46mpg since day one, till this last tank I added 4oz of Power Systems Cetane boost and been using the same pump for fuel (BP as its got the highest Cetane rating in my area) On this tank I managed a trip average of 50mpg. I have gotten several trip average reading of 60.

Look into where you are buying fuel...truck stop diesel is some of the worst from what I read here: http://forums.tdiclub.com/showthread.php?t=200694
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)
Love's: 40
Pilot: 40
Valero: 40
Sheetz: 40
Flying J, 40
Wawa, 40

Cetane levels are important to know (Suggest trying out the Power Systems Additive if you can get it there in Canadia.

Use the cruise on your trip ( I have a hour drive in rolling hills for half of my trip then onto major 4 lane highway )

Maintenance done on the car... air filter and such?

rotarykid · Jul 18, 2014

Well it sounds like you are using proper driving techniques......

Do you keep the rpms low, getting into and staying in the highest gear possible for conditions?? Try to stay under 2k rpms most of time to increase mpgs in your car...

What part of alberta are you in? Flat, plains region or hilly mountainous?? If you have hills to work with add some N time and you will see a mpg improvement.

I had a PD car like yours for a time, with the dsg and with a lot of effort along with N use when conditions allowed I was able to get into the high 40s to just under 50 around Denver. I also saw that when the car was just put in D and driven it easily dropped into the high 30s on my city mixed loops......

How fast do you drive??90, 100, 110, 120+ ?

Have you checked the cam timing, the crank angle sensor setting in relation to the cam? If this is off in your PD car that will kill mpgs...

Good Luck! in your search to see if you can increase your tank mpgs.....

_____________________________________________

And maxst2, you have a different more efficient engine than he does and a manual trans so you will always see higher mpgs that he does......

turbocharged798 · Jul 19, 2014

Keeping the RPMs low is a bad idea for TDI. You want to accelerate hard and keep the RPMs up to keep the turbo on boost. Don't let it drop below 2K unless you are coasting or under very light load.

ATR · Jul 19, 2014

I have a 6mt and am getting a average of 42mpg.
On highways I go ~64mph in 55mph zones, 68 in 60mph zones and 75 in 65-70mph zones. I don't ever really baby the go peddle. Shifts are done between 2200-2500 when I am taking it easy and 4500 when I GOTTA GOOOOOO.

There is one road on my way to work with moderate hills (not too steep) and a speed limit of 50mph that I actually go 50 on since it's a country road with one lane travel in each direction. Keeping it in 5th gear the whole time the RPMs stay right around 1700 or so RPM which is right around where the engine makes it's peak torque. In those conditions even with the hills the avrage mpg seems to stick in the mid to high 40s.

Diesels aren't meant to be babied. Give it the beans at least once a day. And when getting it up to speed onto the highways shift around 3000 rpm. This seems to have worked well for me, hopefully these tips will help you get a few more mpg

Disappointing mpg from 2.0 TDI

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