05 Jetta Wagon getting only 36 MPG !!!!!!!

[IndigoBlueWagon]

I just read the updates to this thread and I wonder how far off 36 MPG really is. If you have lousy fuel, drive 80+ on the highway and otherwise are going between stoplights in typical sunbelt traffic fashion, 36 on a not fully broken-in PD may not be bad. I noticed that when I drove in Montana and Wyoming last August (not as hot but just as dry as Vegas) I got 38 MPG. Wind plus hot diesel may have an impact, along with hills and dry air. The lousy fuel probably also contributes to the smoke. Try some Diesel Kleen and double the dose (about 8 oz. per fill) to raise your centane level and clean out your intake.

For a 3,400 lb car that's solid and comfortable, 36 MPG driving pretty hard is not bad at all. If you had a 1.8T in it you'd be lucky to get 24.

 

[danielttt]

My fuel mileage has dropped a bunch the last several thousand miles. I've had an '05 TDI Wagon since Christmas. Originally was steadily in the low 40's but with the hot weather it's dropped into the 36- 37 mpg range.
I checked the air filter. It's running great. Drive is 30 miles each way to work daily; mostly freeway. I have 15000 miles on the car. Any ideas?

 

[TornadoRed]

I've had an '05 TDI Wagon since Christmas. Originally was steadily in the low 40's but with the hot weather it's dropped into the 36- 37 mpg range.
I checked the air filter. It's running great. Drive is 30 miles each way to work daily; mostly freeway. I have 15000 miles on the car. Any ideas?

First, update your profile so we know where you live. Or at least which climate zone.

15k is not fully broken-in. I drive pretty hard and my mileage didn't plateau til after 20k. For most people it would have taken 40k miles or more to reach that point.

Driving pattern is always a major factor.

But so is weather, and most of North America is in the middle of a hot spell. Air conditioners lower fuel economy, but also hot air lowers the efficiency of the intercooler. So your engine is ingesting hotter air, not producing quite as much power, and you're compensating by pressing down a little harder on the accelerator.

I would guess that the AC alone accounts for about a 2-3 mpg penalty. But if the outside air is 100 degrees instead of 80 degrees, that could account for another 4-5 mpg penalty.

Fuel temperature also enters into the equation. But I have no idea how to quantify that.

Edit: BTW, two weeks ago I got back-to-back 50+ mpg tanks on a cross-country trip. Now I'm back at work and it looks like my current tank will be approx 37 mpg.

 

[LarryLymb]

Widmn, What tires are you using and what tire pressure?

 

[TomB]

I still miss my 2002 Jetta with the VE injection.

54 mpg on trips from Seattle to Portland with B100. Of course the 5-speed tranny.

 

[Bob_Fout]

I still miss my 2002 Jetta with the VE injection.

54 mpg on trips from Seattle to Portland with B100. Of course the 5-speed tranny.

If you got 54 MPG with B100, you'd get 60 MPG with D2!

 

[danielttt]

TornadoRed, The profile is duely updated. Florida is reasonably warm and our humidity would further rob the air's capacity to remove heat from the intercooler...I haven't kept the best records but always check the mileage w/ each fillup. It seems like the mileage started going south after things really started warming up. I've never seen anything above 46mpg and would occasionally see 39 mpg's when driving...shall we say "competitively". 42 / 43 mpg's feels pretty good after other cars i've had and with fuel prices being well past 2 bucks a gallon....mid 30's sucks. Biggest thing is that I like bragging about my fuel mileage to my cohorts and 36/37 doesn't qualify as bragging rights...

 

[milehighassassin]

I have a 2005 Golf TDI PD, and I just hit 10,000 miles. I just did a road trip through South Dakota and I was getting 37 MPG. I was a little pissed, but I ran the AC the entire trip (over 1000 miles), and when I was on the Interstate I was going between 80-90 (mostly 85). When I was on the highways I was going about 55-75, depending on the other cars. Plus I had some stop and go touristy things happening as well. So all considered that is not too bad, plus it was 90+ degrees all day long. When I had my 1.8T I was getting about 24-27 but I had a full exhaust, and full intake including a TIP, so that motor was breathing well.
More updates later on. I have gotten as good as 45 on my car, when I take it easy.

 

[Ben]

Since this thread is still alive I'll post the results from my road trip I mentioned earlier.

I went from Portland to Las Vegas in my first real trip in my TDI. I covered a total of around 2500 miles and four refueling stops. My milage went from a low of 32 (the worst I've gotten) to a high of 41 (the highest I've gotten) with the other two tanks in the high 30's. The lowest figure was more than 50% city driving (in Las Vegas, @ an average of 105 degrees) and 200-300 miles of 80mph desert driving. The highest driving had lower average speeds but was all highway and mostly flat terrain. All tanks were with nearly 100% A/C and averaged out in the 37 mpg range. So I can see how some people are getting crummy milage under the right conditions.

My milage figures are still suspect as I'm still learning to vent... I seem to be putting in a little more fuel each time which may be artificially deflating my results. I think I've almost mastered the technique but since I don't want to overfill the tank and waste fuel, I've been taking things slow.

My wagon still isn't close to being broken in (less then 7k now) so I'm not going to obsess over my "low" MPG figures compared to some people here. It's still a nice improvement over my previous gasser which would have averaged about 26-27 in the same conditions.

The only other thing of note is I also had my first oil change done in Vegas where I suspected they put in the wrong oil. I returned home and talked to my local dealer who claims that even though the part number is for the old oil, it's really the new 505.01 spec oil so I don't know what to think at this point. I don't see why they would make something up to cover the ass of another dealer 1100 miles away yet I'm still not completely convinced. I guess I should just take the advise of one club member and do the oil changes myself, which is what I did from my very first car until I got my Ford Focus. After two oil changes in that thing, I was so frustrated by the oil filter location I've paid to have it done ever since.

--Ben

 

[supton]

The TDI is really nice for oil changes; it can be done completely from the topside. It's really nice. I still wear disposable gloves, but otherwise consider it easy and clean.

I'm not sure what there is to master about "venting"; I've always gone until I see fuel. Go until the pump clicks off. I suppose you probably haven't removed the vent guts; so you have to push on the button with the nozzle. Now, with 1/2 to 3/4 of the pump flow (squeeze to 1/2 or so on the pump lever), let fuel go in at a fast rate. It'll take maybe 30 seconds at 1/2 flow to get 'bout 1 gallon or so in there, then you'll see the foam rise up in the filler area. Stop, and let it go down for say 5 or 10 seconds. Then, use maybe 1/4 of the pump flow. Repeat until full.

As you do this a few times, you'll automatically reduce pump flow as you see foam rise up, and when it settles down you'll increase flow, w/o ever stopping the pump. Towards the end, you'll notice that the foam never really dissappears; I usually willl stop, and "tap" the foam to see if it will break and show the fuel at the top of the filler neck.

After 42k (that's like 63 fillups for me), it's almost second nature.

 

[myke_w]

talked to my local dealer who claims that even though the part number is for the old oil, it's really the new 505.01 spec oil so I don't know what to think at this point.

If they have the old part number on the invoice they used the old oil, period. That's a major snafu IMO. if anything goes wrong with your engine you have them by the balls. I would call volkswagen of america to file a formal complaint and find out what they'll do about it. If that means tearing the motor down for inspection then so be it, it will be better in the long run. If you must see a dealer, post on here to find a better one than the local lying bastards.
At the very least you need to get that oil out of your motor now. The part number that you need to see on the invoice is G 052 167A2. Best luck, and please let us know what dealerships you are using so we can avoid them.

 

[tongsli]

So I'll go ahead and add my 2 cents like everyone else and at the risk of sounding like a broken record...

Both our TDI's increased in mpg with the increase in overall mileage. I think they all do pretty much the same thing.

When I cleaned the intake of my 2000 TDI at 60K, it also went up(mileage) and I got power back.

L

 

[Mike_M]

I'm not sure what there is to master about "venting"; I've always gone until I see fuel. Go until the pump clicks off. I suppose you probably haven't removed the vent guts; so you have to push on the button with the nozzle. Now, with 1/2 to 3/4 of the pump flow (squeeze to 1/2 or so on the pump lever), let fuel go in at a fast rate. It'll take maybe 30 seconds at 1/2 flow to get 'bout 1 gallon or so in there, then you'll see the foam rise up in the filler area. Stop, and let it go down for say 5 or 10 seconds. Then, use maybe 1/4 of the pump flow. Repeat until full.

The best write-up of venting I've seen yet.

One dumb (and slightly off-topic) question, if I may?

The pump still stops automatically after you've done a ventectomy? So I don't have to worry about spilling fuel unless I'm ham-handed with the nozzle after that, right?

Mike

 

[vikingrob]

Yes, it does, but I do watch over it, especially after an experience with a pump that did not shut off automatically about a month before the ventectomy.

Watching is much easier on a Beetle.