2009 Jetta TDI fails to meet VW's Predictions

The Prius engine operates at almost full-throttle for most of its operation and thus avoids minimizes pumping losses.

The engine output is controlled by varying speed but keeping the throttle constant.

kevin

 

Will blue motion arrive before the bar is raised?

 

Yes, it's a nice system. The CVT-like characteristics of the HSD allow this to work, plus the low end torque of the electric motors makes it possible to use an Atkinson cycle engine. It's a win-win setup.

Tom

 

Thank you for correcting me. I majored in biochemistry, not industrial chemistry. It has been a long time since I took o-chem. What you typed about the reason that Toyota chose the electric system is very interesting. I believe you and I am not challenging you at all, but I find it odd that the regenerative braking only contributes about 2% to improved economy. (2% means 50mpg goes to 51mpg) A lot of Prius drivers claim how they can drive quite a distance on electric only. That's a lot of energy that has been stored. Of course, yes, electricity is also generated while the gasoline engine is operating, which also contributes, but doesn't that defeat the purpose? (anytime you convert one form of energy to another, there is a loss).
Just out of curiosity, what is the thermal efficiency of the a normal gasoline engine? A diesel? How does greater compression ratio result in increased efficiency? Does it somehow reduce adiabatic loss?

"a more diesel-engine-like 13:1 expansion ratio. This enables a peak thermal efficiency of 36%, and is the key reason for the Priuses improved economy." But the city mpg SAVINGS are greater than the highway mpg savings, which would reflect that the electric motor being used for acceleration would be the main reason. Again, I am not trying to correct you, I am just having a discussion and trying to learn something. Thank you.

Thank you.

-----------------------------------
Also, I have notice that the average driver tends to save the most with a Prius. The average person seems to get about 40-45mpg in a Prius, yet the average hypermiler seems to get 50-55mpg (the Prius seems to have the most savings for the average driver). Maybe you have observed something different. In my own driving, accelerating from zero seems to be where the most savings/waste are observed; an electric assist would be most beneficial, as is reflected in the city versus highway EPA numbers for the Prius.

 

I’m not saying that a Jetta TDI will cost less per mile than a Prius. The Prius has the lowest fuel cost per mile of any car available in the US. However, there are a lot of people than won’t buy a Prius for many reasons. (It’s ugly, it’s a hatchback, it’s a “tree-hugger carâ€, the battery only lasts 50K miles, it handles like crap, it’s Japanese, etc, etc) Lots of people love to hate the Prius for real or imagined reasons.

VW dealerships will sell it against conventional small to mid-size sedans. They will sell it based on the fact it is European, has a sporty ride, above average interior, etc. When someone says “But diesel cost so much and you have to go to a truck stop to get fuel†the salesman has to be ready to correct misconceptions and sell on strengths:

It only costs $/mile compared to competitor XYZ at $/mile.
There are X diesel stations in town
The TDI goes 600 miles or more on a tank so you will have plenty of time to find fuel
Diesel engines last 300K plus miles
Diesel vehicles have X % higher resale value after 4 years.
You will get a $$$ tax rebate on your federal taxes for the TDI.
Etc, Etc

If you look at the chart below you will see that the VW TDI is in the top ten list for lowest fuel cost per mile even with diesel 19% higher than regular. That is not a bad place to be.

Vehicle------------------Mileage--------Fuel----------$/gal------$/mile
Prius Hybrid--------------48/46/45------Regular-------$3.79------$0.082
Civic Hybrid--------------40/42/45------Regular------$3.79-------$0.090
Smart Coupe-------------33/36/41-----Premium-------$3.94------$0.110
Camry Hybrid-------------33/34/34-----Regular-------$3.79-------$0.112
1.5L Yaris----------------29/32/36------Regular------$3.79-------$0.118
1.5L Fit------------------28/31/34------Regular------$3.79-------$0.122
1.6L Mini Cooper---------28/32/37-----Premium-------$3.94-------$0.123
1.8L Corolla--------------26/30/35-----Regular-------$3.79-------$0.126
1.8L Civic----------------26/29/34-----Regular-------$3.79-------$0.131
2.0L TDI Jetta----------30/34/41-----Diesel------$4.49------$0.132
1.8L Versa---------------26/28/31-----Regular-------$3.79------$0.135
2.0L Mazda 3------------24/27/32-----Regular--------$3.79------$0.140
2.0L Sentra--------------24/27/31-----Regular-------$3.79-------$0.140
2.4L Sonata--------------21/25/31-----Regular-------$3.79------$0.152
2.4L Camry---------------21/25/31-----Regular-------$3.79------$0.152
2.4L Accord--------------22/25/31-----Regular-------$3.79------$0.152
2.4L Malibu--------------22/25/32-----Regular--------$3.79------$0.152
2.4L Scion XB-----------22/24/28------Regular--------$3.79-----$0.158

(BTW, my fuel prices per gallon are the national average as reported by the DOE: Gasoline and Diesel Fuel Update)

 

When the Mercedes R320 CDI was introduced in Canada, dealers promised fuel economy in the low 40's, highway. For a nice solid "station wagon" with a curb weight approaching 6,000 lbs, that was impressive

Ah, but Canada also introduced tougher diesel emissions. Not as tough as the EPA T2B5, but tougher. That Mercedes is now rated in the low 30's highway

Once the urea injection comes out, I wonder how they will keep the fluid from freezing in our -40 winters? Add methanol to it??

 

I agree that Toyota, along with GM and Ford, have to be doing a 'Yesssss' with appropriate arm pumping.

The Jetta is Prius-sized but nowhere near the Prius in overall fuel economy. It's barely better than the gasser Corolla or Civics but about equal when factoring in cost of fuel ( see above ). It's just equal to the Hybrid Camry/Altima which are much larger vehicles. It probably will be just about equal to the future hybrid Fusions/Malibu/Aura as well.

Huge marketing faux pas by VW IMO. Then.......... it's a VW with all that baggage to carry around as well.

Cliff Notes: Nice vehicle but non-factor in the US. Next case.

But then in a masterful bit of serendipitous timing the Gen 3 Prius arrives... faster and more fuel efficient.

 

First, the Jetta is (or at least was) smaller than my Prius. Second, the driver has a great influence on FE. Here are the results from last year's rally, The Tour to the Shore. I don't have the model years of the cars. So a smaller diesel can do say 10% better than a Prius but their additional fuel costs are much more than 10%. On a cost per mile basis the race isn't even close.

Insight Hybrid 79.88
Attack Biodiesel 66.52
Prius Hybrid 63.74
Jetta Diesel 62.03
Jetta Biodiesel 59.30
Prius Hybrid 58.65
Prius Hybrid 56.68
Insight Hybrid 54.94
Prius Hybrid5 3.82
Jetta Biodiesel 44.47
Prius Hybrid 44.23
Camry Gasoline 33.53

 

Yes and no.

The Jetta Sedan is smaller than the Prius but the Wagon is larger. (Both 4th and 5th generations) (The wagon and sedan are rated the same for EPA fuel mileage)

EPA interior volume (passenger/cargo/total) in cubic feet:

03 Jetta Sedan:-----87/13/100
08 Civic Hybrid------91/10/101
08 Civic Sedan------91/12/103
09 Jetta Sedan:-----91/16/107
08 Camry Hybrid----101/11/112
08 Prius-------------96/16/112
08 Camry Sedan----101/15/116
03 Jetta Wagon:-----89/34/123
09 Jetta Wagon:-----92/33/125

My experience has shown the Prius to have a lower cost per mile for fuel.

My wife's Prius has averaged $0.06 / mile since Feb-07
My Jetta Wagon TDI has average $0.07 / mile in the same period

(Edit, corrected TDI $/Mile from $.70 to $.07)

 

Apart from all of the electric vehicles!

If you're paying 10 cents per kWh for your electricity, it's equivalent to around 2 cents per mile in a Tesla EV, or a neighbourhood EV etc.

 

Hey all, I thought I would give you my review of the Jetta TDi post test-drive.

After owning the Prius for a year, I wound up selling my 9-2X privately in hopes of getting in on the Jetta Sportwagen with its HIGHLY ACCLAIMED (at the time MPG's). While we love the PRius, I wanted a true manual with a little oomph. I assumed this would meet my needs. I had called a dealer back in March-Apriil to have them call me when it came in to drive. I only want a wagon/ hatch and I only want stick (those were my reqs). I FINALLY got the call this week stating they had them for test drives >>> On to the review already, geez!

Sedan with DSG (auto) available to test:

The TDI will only be offered in one trim level >>> TDi (which is comparable to SE). You can choose Wagon or Sedan, Manual or DSG, Nav system and add Sunroof. That's it! No more options, fabric selections etc. The trim gives you most of the crap you would ever want >> PW, PL, keyless entry, power seat back (not the whole seat), AM/FM/ Sirius, Some real nice cubby spaces here and there, heated seats, Manual HVAC.
The part that BLOWS IMO is the cheesey Leatherette seat cover/ fabric. Leatherette= Vinyl. No cloth option, no leather option, only CHEESE option. Steering wheel is also covered in leatherette. I've always considered the VW's interiors to be a notch above, but I think the materials look cheaper than before and the Leatherette spoils it all imo. Although, I will say it's better than the Prius hard plastics. I will no longer think of VW's interior in their economy car as anything other than all the rest ... ECONOMIZED.
I looked at the wagon in gas version on the lot. The car is truly fantastic when the rear seats are down. More room than most small SUV's. Look up the cargo numbers. It will surprise you. I believe it beats the Prius in all but TOTAL interior volume.


So how's it drive?
Start it up and you wouldn't know it's a diesel in the cabin unless you really listened. Outside the car idles like a QUIET diesel engine. No smoke from the exhaust. Put it in gear, put your foot in it and hold on. THis baby has some real power. You really feel that torque kick, and I was actually Grinning from ear to ear. When you get on the freeway, you have IMMEDIATE passing torque. This thing hauls serious butt.
HOWEVER >>> The tach runs to 4500 which comes up awfully quick. I got caught by surprise a couple times using the DSG in manual mode. You shift into 3rd real fast with this car. It makes me think a 6-speed manual may be a real workout in stop and go. 5 speed makes more sense to me.
Handling was pretty much everyday car. Nothing great, nothing bad. Definitely more stable than the Prius but not something you'll hit the track in without modification.


Well, MPG's, MPG's???
I whinned about the crappy gov't #'s (29/40 or something on the sticker). I mean diesel cost 20%+ more than gas around me. So that immediately knocks those mpg's down by 20% in my mind. VW went and hired their own tester who claims 35/45 or something. They even put this on the sticker. I was skeptical with the whol "hired tester thing." That being said, I watched the current mpg's on the computer and I saw high 50's -low 60's being achieved at 70mph. Of course my around town run was no where near that and the car runs at idle so you burn fuel. It seems like this thing has potential to get some good #'s after you learn to drive it.



My package to consider would be the Diesel Sportwagen with Panoramic Sunroof and Manual 6 speed. Came to $25540 delivered. Darn competitve price when measured against a comparable Prius.
I like the PRius interior better, but I like the Jetta drivability better. It could be a nice complement to our '07 Prius in the garage. Although, my current DD ain't doing too shabby right now either.

 

Unfortunately I can't say I'm surprised. This has become the MO for VW it seems. Hype up the cars mpg before it is released and then hope no one notices the actual mpg is much lower than touted.

Hopefully they have made improvements on the emissions front though.

 

The EPA ratings are low for diesels because the test methodologies were written based on data for and from conventional gasoline powered vehicles.

The is from the EPA official report on how EPA ratings are done:
Final Technical Support Document: Fuel Economy Labeling of Motor Vehicle Revisions to Improve Calculation of Fuel Economy Estimates

Page 3:
"Because the 5-cycle method is inherently vehicle-specific, the difference between today’s values and the new fuel economy estimates could vary widely from vehicle to vehicle. Our new approach will result in city fuel economy estimates that are between 8 to 15 percent lower than today’s labels for the majority of conventional vehicles. The city mpg estimates for the manufacturers of most vehicles will drop by about 12 percent on average relative to today’s estimates. For vehicles that achieve generally better fuel economy, such as gasoline-electric hybrid vehicles, the new city estimates will be about 20 to 30 percent lower than today’s labels. The new highway fuel economy estimates will be 5 to 15 percent lower for the majority of vehicles, including most hybrids. The highway mpg estimates for the manufacturers of most vehicles will drop on average by about 8 percent, with estimates for most hybrid vehicles dropping by 10 to 20 percent relative to today’s estimates."

Page 8:"As can be seen, diesels appear to perform the best with respect to their label fuel economy, outperforming the label by 4.3%. Conventional gasoline vehicles come very close to meeting their label, falling short by only 1.4%. Conventional vehicles with relatively high combined fuel economy (here assumed to be 32 mpg or more, representing the top 10% of conventional vehicles in terms of fuel economy) performed only slightly worse, falling short by 1.7%. Hybrids fall short by a much larger margin, 8.2%. Thus, the greater shortfall seen with hybrids appears to be more related to hybrid technology than to simply high levels of fuel economy.

With respect to the mpg-based label values, diesels still perform the best of the four types of vehicles, now exceeding their label values by 18%. Those conventional vehicles with relatively high fuel economy fall next, followed by the typical conventional vehicle and hybrids."

(Note: The first paragraph is referring to the old EPA ratings used prior to 2008. The second paragraph refers to the new 2008 ratings.)

As you can see the EPA realizes they are underestimating the fuel economy of diesel vehicles by 18% be using the same weighting and adjustments for gasoline vehicles as diesel vehicles. For example, the EPA does a across the board reduction of 9.5% to account for loading from grades and cargo plus the use of ethanol. Diesel outperform gasoline vehicles at higher loads and don't use ethanol so this doesn't apply to diesels. See below:

Page 3:
There are many factors that affect fuel economy that are not accounted for in any of our existing test cycles. These include road grade, wind, tire pressure, heavier loads, hills, snow/ice, effects of ethanol in gasoline, and others. We are finalizing a 9.5% downward adjustment to account for these effects.

There are some in the diesel community that believe that the EPA is specifically biased against diesel vehicles and are attempting to reduce their acceptance by down rating their fuel economy so diesels won't qualify for federal tax rebates for high-mileage clean diesels. I choose to believe that there just aren't enough diesel vehicles in the market for the EPA to bother setting a specific standard that rates diesels correctly.

My experience has shown that my 2003 TDI will achieve the old EPA sticker estimates while my Prius gets the new 2008 EPA estimates.

 

FYI, I just posted a new thread with details on the 2009 TDI emissions here:
http://priuschat.com/forums/prius-h...w-jetta-tdi-emissions-results.html#post656028

Rob