thanks, this add some credence to the numbers as I've had zero issues averaging 31mpg on the highway in the jetta or gti. though still disappointing for the TDI.

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For comparison, the European Honda Accord Diesel sedan (our 2009 Acura TSX with the upcoming Diesel motor) has the following consumption figures according to their German website:

urban: 7.3 l/100km (32 mpg)
extra-urban: 4.6 - 4.8 l/100km (49-51 mpg)
combined: 5.6 - 5.7 l/100km (41-42 mpg)

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So the TSX will likely turn the same 30/41 here as the Jetta.

Thanks for the info. It's good to see someone doing some research instead of just whining about EPA lowballs.

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Keep in mind that it is not the same engine:

EU Jetta - 2.0 TDI 4cyl 16v Bosch Pump-Injector
US Jetta - 2.0 TDI 4cyl 16v Bosch Common Rail

The Pump-Injector 1.9 8v engines were very efficient. The 2.0 16v not so much. The old 1.9 8v iron-block has a following cult here in europe. Race applications have about 260hp!

The new common-rail engine is supposed to be more efficient, at least from what one can deduce from the numbers made available when the A3 was facelifted.

One thing's for sure. The CR engine is smoother, quite and revs to 5000rpm...

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the new EPA ratings are VERY accurate. You diesel lovers are in fantasy land. If you look at road tests in ANY major US auto mag you will see their test mileage is typically right in between the EPA city and highway figures as they should be. There is no proof that the new EPA procedures are flawed. In fact, on my car they are still too optimistic in city driving. The diesel Jetta will return real world mileage that is reflective of its EPA ratings just like almost every other car on the road.

BTW, the new EPA numbers are very accurate for the Prius. Most tests have returned 40-45mpg in the Prius and that is exactly how its rated under the current system.

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I'm sure some people are just making their point considering their personal experience.

I've driven diesel cars all my life and paying for the fuel so I am sure that those numbers are low. All my friends and family have also diesel cars.

But if gas had the economic advantage over here I would ditch diesel right away. No fanboism here. Just facts man...

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No need to apologize for facts.

The Prius was adjusted because it's original numbers were far too optimistic. Virtually no one was seeing the mileage numbers that it was touted as having. So, it was adjusted and now seems much more in line with real-world figures.


The difference is that the TDI's never had the same problem. They routinely achieve over the EPA figures, yet they do not get adjusted.

Not to mention that the '09 TDI is a larger, more powerful engine than the previous one. To achieve better mileage figures with that is impressive. Especially since the additional emissions equipment is said to have hurt the efficiency.

For more proof of the TDI's efficiency, here is an artiicle about the '04 Passat TDI http://www.motortrend.com/roadtests/sedan/112_0409_2004_volkswagen_passat/index.html

They averaged 38mpg(which was the EPA hwy figure using the old method) over 300 miles of mixed driving. In a fairly large car. Their "average" matched the highest figure the EPA gave the car and that was before the new guidelines. The revised guidelines put it at 23/34 with a 27mpg combined figure. Pitifully far off from real-world figures.

Here's another link of a comparison between the Prius and an '05(Mk4) Jetta TDI. http://www.automobilemag.com/reviews/sedans/0409_toyota_prius_volkswagen_jetta_diesel/performance.html

FWIW, they measured 34mpg city and 43 hwy compared to the 52mpg city they saw in the Prius with no quoted hwy mileage. That's when the Prius was rated at 61mpg city as well. So, the TDI again bettered the EPA figures. How many more links would you like?

These are also from auto magazine which typically aren't out to squeeze the best mileage out of every car and likely have heavier feet than most of us. Not to mention that VW's TDI models are not purpose-built to achieve high mileage like the Prius is. They are simply the regular models with a different engine.

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One more note.

The Prius also happens to have 0-60 time of around 11sec. But somehow, that's a knock against the Jetta? The VW figures though were using the older, 100hp engine. The new one has 140hp and significantly more torque. While they won't be drag strip stars, I think the TDI's will hold up well against other vehicles that attain similar mileage.

Plus, they are geared differently than the gas models due to the lower redline. So I'm unsure of how that would affect the passing performance.

One quick story relating to the passing ability though. I had the opportunity to follow a TDI Jetta(MkIII) for about 20 miles a few winters back on my way to a snowboarding trip. There were times that we touched 115mph with the Jetta still in front of me. While I didn't attempt to overtake him, I was surprised by the acceleration that the TDI had even at those speeds. I didn't have to be at full-throttle to keep up, but it was more than I expected. This was at an elevation of about 8000-8500ft also. I would not be terribly concerned about the passing ability of a modern TDI.

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Because the Prius only uses 40% of the total charge range of the battery pack, the batteries do not decrease much in capacity over the life of the pack. There are plenty of Prius taxis that are doing just fine. Yes, the pack will have to be replaced at some point. Toyota isn't making press releases about it, so we don't know how long they last on average, but again there have been informal polls of taxi drivers even those who had Priuses for a long time (since the first 2nd gen models) seem to be on their first pack.

As to the EPA ratings being low on this VW, well, I have a friend who drives his Prius every day about 40 miles and he averages 53-54mpg. It's rated at 45 now. So remember, you cannot compare optimistic fuel ratings of the car you like to EPA ratings of the one you don't. It's not a valid comparison.

If you're looking to crap on hybrids, you could mention that in cold weather, the battery pack cannot deliver its charge and thus has a reduction in capacity. This is temporary and it returns when the weather warms back up. But on a 30 degree day you're going to use more gas than on a warm day.

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The site clearly says "We have revised the 1985-2007 MPG estimates to make them comparable to EPA's new 2008 MPG ratings."

So yeah, they lowered the figure on the 2005 Jetta. This didn't actually decrease anyone's fuel economy of course.

Note though that those older cars were not tested under the new system, they just kinda did some adjusting of the figures across the board. So there is some significant margin of error. So the 41 in 2009 doesn't necessarily mean the new car gets better mpg than the 2005 which lists 5% less at 39.

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Yes, the EPA did adjust those figures as I noticed and posted on another forum as well.

But, with the '05 and '06 TDI's(the two years it was available in the new body style with the TDI), owners are still seeing significantly better mileage than the EPA estimated. The '05 TDI's are listed at 31/39 but most owners report highyway mileage in the mid to upper 40's.

With the new engine showing even better EPA mileage, I wouldn't be surprised to see owners getting around 50mpg hwy. Time will tell and the time is coming soon.

Interesting to note that the fueleconomy.gov page for the '08 Prius shows 48/45, but underneath, they list what actual drivers are seeing. The range goes from 36-56mpg with an average of 45.8MPG. I'd be very interested to see how a similar comparison would look for the '09 Jetta TDI.

It's definitley true that individual drivers will have significantly different figures due to driving style. But, I'd be willing to bet that attaining high mileage in a TDI will be much easier than achieving high mileage in a Prius. In other words, you can drive a TDI like a regular car and still get great mileage.

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Found it: You just have to click on the model of each car and it will give you the same info I found on the Prius. It came up right away for the Prius because there is only one model available.

Anyhow, I looked at a couple of years of each and in every case, the actual driver's estimates of mileage were higher than the EPA HWY numbers for the Jetta TDI and lower than the EPA City figures for the Prius(the highest number listed for each). That runs right into the theory I floated in my post above.

For instance, the '07 Prius lists an average of 46.5MPG(compared to a 46MPG combined EPA figure) from 125 drivers with a low of 32MPG and a high of 71MPG. The '06 Jetta TDI 5spd manual lists an average of 41.9MPG(compared to a 33MPG combined EPA figure) from 51 drivers with a low of 35 and a high of 54. Note that the lowest driver's figure is still higher than the EPA combined figure for the TDI.

The Jetta figures seem to be far more repeatable just judging by the 39MPG range from low to high for the Prius and the 19MPG range for the TDI. Nonetheless, it seems that the TDI's are much more willing to give better than EPA figures than the Prius(and probably most hybrids).

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