According to fueleconomy.gov the 2008 Jetta TDI has a better CO2 score and a slightly worse air pollution score than gasoline-powered 2008 Jetta. That is, except in California, where the gasoline Jetta is PZEV and has a much better air pollution score. Fueleconomy.gov doesn't have air pollution data for older cars, but I'd be surprised if a '70s car is anywhere as clean as a modern "clean diesel". Whenever I'm behind an older car (e.g. '60s or '70s) on the road I can smell the exhaust.

At this point gasoline cars can be made to run cleaner than diesel, but good diesels are pretty clean. They are cleaner than many gasoline cars of just 5 years ago. For example, on an air pollution scale of 1-10 with 10 as best, the 2008 Jetta TDI score is 6 and annual tons of CO2 emitted is 6.2. The 2005 Jetta 1.8L (gasoline) score is 3 and CO2 is 8.3.

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A 70's car, sans a catalytic converter would likely lose, but yea "clean" diesels are about the same as the worst gasoline cars.

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This filter isn't capturing "pollutants" in general, it is capturing particulates. And gas cars don't produce particulates at idle, even back in the 70s.

paulwesterberg:
70s cars had catalytic converters (75 onward) and catalytic converters don't do anything for particulates.

You could get a 70s gas car to produce some particulates at WOT (wide-open throttle), but then it'd just blow a hole in the coffee filter due to airflow (and thus would be a pretty lousy test).

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And how old do you think EVs are?

http://en.wikipedia.org/wiki/Electric_vehicles#History

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Mark 5:16PM (5/04/2009):

> I am disappointed that VW are pushing diesel
> so much and not going for hybrids or plug-ins.
> Gas and Diesel engines are 100+ year old
> technology we need to move on from them.

The reason is very simple. Volkswagen invested millions in diesel technology while their key competitors went for more fuel efficient and environmentally friendly hybrids (which are simply an introduction to plug-in hybrids with gradually more and more all electric range/stronger electric assist, the next step in transition from crude oil energy).

So now they'll put every possible effort into misleading customers, while carefully hiding the fact of diesel unnecessary complexity and higher ownership costs. Which are very convenient for a car maker since they mean charging customers more.

Why didn't Volkswagen say in this commercial that:
- 2009 VW Jetta TDI Clean (?) Diesel gets EPA air pollution rating of 6 out of 10, despite using both particulate filter and NOx trap
- 2004 Toyota Prius II gets EPA air pollution rating of 8 out of 10, not needing any of those devices (which will likely decrease maintenance and repair costs)

Sources:
- http://www.fueleconomy.gov/feg/2008car1tablef.jsp?id=25262
- http://www.fueleconomy.gov/feg/compx2008f.jsp?year=2004&make=Toyota&model=Prius&hiddenField=Findacar


Why didn't Volkswagen say that diesels they make in Europe mop the floor of 850+ ADAC EcoTest rating?

Source: http://adac-ecotest.awardspace.biz/

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downtoearth:
Hybrid power trains are complex. Probably more complex than diesels with emission control systems. The fact that they are reliable is credit to the companies that make them. We know VW can make reliable diesel engines; hopefully they can make the new versions with the additional systems just as reliable.

It's a safe bet that VW is working on reducing the cost of clean diesel power trains. At some point it will be possible to make a cost-competitive diesel hybrid.

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We don't know anything about the reliability of the new clean diesels. I have been reading TDIclub because I am considering a TDI for my next car, but what I see doesn't fill me with hope. On essentially new 2009 clean TDIs there have already been a few turbo failures, and issues with the particulate filters (seems they don't like many short trips, no time to burn off particulates).

I would feel fairly confident the Prius will be cheaper to maintain even if you do have to replace the battery.

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slk23 6:07PM (5/04/2009):

> Hybrid power trains are complex. Probably more complex
> than diesels with emission control systems.

This is an utter myth.

Full hybrids like the Prius need:
- two additional electric motors (in fact one cause you need no starter) - electric motors aren't actually problematic, are they? It's just a coil wiring and some ball bearings, lasts for huge mileages in electric vehicles
- an inverter, which has no moving parts
- a battery, which has no moving parts as well

Compare it to 2009 Jetta TDI DSG (automatic to automatic to compare fairly):
- Jetta has a complex double plate clutch with hydraulic actuators which also wears; Prius has NO CLUTCH
- Jetta has a very complex automated gearbox with mechanical/hydraulic actuation; Prius gearbox is just an immovable single set of planetary gears, this thing will last forever with no things in it to go wrong
- Jetta has an ultra high pressure fuel pump (~2000 bar); Prius has lazy low pressure port injection (100 bar?) cause it does not need high power (electric boost) and clean burning mixture is achieved simply by fuel evaporation
- Jetta has very expensive and fragile high precision injectors; Prius has simple, low pressure ordinary port injection
- Jetta has a variable vane turbocharger which never lasts as long as the entire car; Prius needs no such thing thanks to Atkinson cycle
- Jetta has a double mass flywheel, a device know for going wrong often in diesels; Prius has no such thing
- Jetta has a particulate filter to clean its exhaust, Prius needs no such thing
- Jetta has a NOx trap, all this stuff needs to be carefully managed by onboard computers fed by multiple sensors; Prius needs no such overkill

Sorry, but modern high precision diesels are vastly more complex than any hybrid is. Various writers simply imputed the word "compex" with a hybrid just because it seems so for laymen.


> It's a safe bet that VW is working on reducing
> the cost of clean diesel power trains. At some
> point it will be possible to make a cost-competitive
> diesel hybrid.

A diesel hybrid makes no sense. It will achieve nearly identical fuel EFFICIENCY (not to confuse with economy) and will still require all the complex modern diesel technology instead of a ruthlessly simple gas similarly efficient Atkinson cycle gas engine.

It's much better to put the 2xpremium into larger battery for longer all electric range/stronger assist. This will truly reduce fuel consumption even further while cutting dependency on foreign oil.

By the way, the spread of emissions from diesels and hybrids is highest in towns where population density is often 2000+ people per km2. Why no one mentions this massive hybrid advantage?


Snowdog 6:23PM (5/04/2009)

> On essentially new 2009 clean TDIs there have
> already been a few turbo failures, and issues
> with the particulate filters (seems they don't like
> many short trips, no time to burn off particulates).

> I would feel fairly confident the Prius will be cheaper
> to maintain even if you do have to replace the battery.

I'll put it simply and straightforward: diesels work in trucks. They just don't work in cars.

Hybrids vs diesels vs gassers comparison:
- 5-year REAL LIFE COST OF OWNERSHIP: fuel, repair and totals (fuel, repairs, maintenance, financing, depreciation, taxes, insurance)
- environmental impact


Fuel costs:

Toyota Prius II Hybrid:______$5,285 [1]
Honda Civic Hybrid:__________$6,076 [2]
VW Jetta 1.9 TDI DIESEL:_____$8,742 [4]
VW Jetta 2.0 GLI gas:________$10,330 [3]
VW Jetta 180HP gas turbo:____$11,175 [5]


Repairs:

Toyota Prius II:_____________$2,291 [1]
Honda Civic Hybrid:__________$2,365 [2]
VW Jetta 2.0 gas:____________$2,684 [3]
VW Jetta 180HP gas turbo:____$3,066 [5]
VW Jetta 1.9 TDI DIESEL:_____$3,540 [4]


TOTAL costs of ownership - 5 years:

Honda Civic Hybrid:_________ $28,359 [2]
Toyota Prius II:____________ $29,669 [1]
VW Jetta 2.0 gas:___________ $30,451 [3]
VW Jetta 180HP gas turbo:___ $33,859 [5]
VW Jetta 1.9 TDI DIESEL:____ $34,305 [4]


EPA Air Pollution Score (the higher the better):

Toyota Prius II:____________8 out of 10
Honda Civic Hybrid:_________6 out of 10
VW Jetta 2.0 gas:___________6 out of 10
VW Jetta 1.9 TDI DIESEL:____1 out of 10
VW Jetta 180HP gas turbo:___not available


0-60 times:

VW Jetta 1.8 Turbo gas: ____7.7 sec (180HP)[10]
VW Jetta 2.0 gas____________~10.5 sec
Toyota Prius II:____________10.9 sec [12]
Honda Civic Hybrid:_________12.4 sec [12]
Vw Jetta 1.9 TDI____________14.9 sec (90 HP) [11]


Environmental performance: by driving a Toyota Prius II over 310.000 miles (battery lifespan [6][7]) instead of Volkswagen Jetta 1.9 TDI you save 2090 US gallons of crude oil and emit 27 TONS CO2 less.

__________________________
Toyota Camry Hybrid vs VW Passat B6 TDI DIESEL vs Nissan Altima Hybrid vs Honda Accord Hybrid
- 5 year TOTAL COSTS of ownerhip
- environmental performance

Fuel:

Toyota Camry Hybrid:_____$7,365 [1]
Nissan Altima Hybrid: ___$7,175 [3]
Honda Accord Hybrid:_____$8,717 [2]
VW Passat B6 TDI DIESEL: $11,625 [4]


Repairs:

Toyota Camry Hybrid:_____$1,353 [1]
Nissan Altima Hybrid:____$1,353 [3]
Honda Accord Hybrid:_____$2,074 [2]
VW Passat B6 TDI DIESEL:_$3,373 [4]


TOTAL costs:

Nissan Altima Hybrid:____$36,751 [3]
Honda Accord Hybrid:_____$36,148 [2]
Toyota Camry Hybrid:_____$37,972 [1]
VW Passat B6 TDI DIESEL: Totals: $41,219 [4]


0-60 time:

Nissan Altima Hybrid:____ 7.6 sec [5]
Toyota Camry Hybrid:_____ 8.4 sec [5]
Honda Accord Hybrid:____ ~8.0 sec [6]
VW Passat B6 TDI DIESEL:_ 10.4 [7]


EPA Air pollution score:

Toyota Camry Hybrid:_____ 8 out of 10 [8]
Honda Accord Hybrid:______6 out of 10 [9]
VW Passat TDI DIESEL:_____1 out of 10* [10]
Nissan Altima Hybrid:____ not available

* diesels with added particulate filters and NOx traps/AdBlue injection are likely to get 6 out of 10, exactly as 2009 VW Jetta TDI

Clean (?) Diesel got [11].


ENVIRONMENTAL PERFORMANCE:

By driving a Toyota Camry Hybrid over 310.000 miles (battery lifespan [12][13]) instead of a VW Passat TDI DIESEL you save ~1870 US gallons of crude oil and emit 23 TONS of CO2 less [14].


See this article comments for references:
http://www.autospies.com/news/Why-Are-Car-Companies-So-Skittish-About-Bringing-Smaller-Displacement-Clean-Diesels-To-the-USA-43414/

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downtoearth:
I doubt you'll find many that would agree with you. The fact is the HSD is not simple. It's complex and highly refined. That does not imply it's unreliable. Modern "clean" diesels aren't simple either, but your comparison is unbalanced and biased.

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@ downtoearth -

>By the way, the spread of emissions from diesels and hybrids is highest in towns where population density is often 2000+ people per km2. Why no one mentions this massive hybrid advantage?<

Because it's not an advantage for hybrids in those locations. Hybrids, including the Prius, have higher emissions of hydrocarbon (including evaporative VOC emissions) than the 2009 Jetta TDI.

All U.S. metropolitan areas studied thus far by DOE/NREL have been shown to be VOC-limited with respect to ozone formation (i.e., "smog") (ref. Blanchard, Tanenbaum, Lawson; “Differences between Weekday and Weekend Air Pollutant Levels in Atlanta; Baltimore; Chicago; Dallas–Fort Worth; Denver; Houston; New York; Phoenix; Washington, DC; and Surrounding Areas.” Journal of the Air & Waste Management Association, Volume 58, December 2008, Pages 1598–1615). In essence, this means that hydrocarbons are responsible for ozone accumulation in these areas, not NOx.

Since these metropolitan areas are where most of the non-attainment with the ozone NAAQS occurs and where most exposures to unacceptably high ozone levels occur, you need lower HC emissions in these area to effectively lower ambient ozone levels, which is better achieved with the Jetta TDI.

The DPF takes care of the PM emissions, so they are a non-issue.

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@slk23. "The fact is the HSD is not simple. It's complex and highly refined. "

Ahh no. It's not a fact. The Prius it quite simple mechanically. The new generation even more so. It is brilliant in its simplicity. Here are some simplifications to reduce maintenance.

Belt Free: There isn't a belt on the car anywhere. Accessory belt gone. Timing is done with a chain. VW has both accessory and timing belts. Go price a TDI timing belt replacement (prepare to weep).

No transmission: The Toyota has simple planetary gear power coupler. There are no clutches, no belts, no chains, no band and no actual changing of gears. Ultra reliable and simple. VW has gears/clutches, lots to go wrong and wear out.

Emission System: Simpler Gas emissions system, not clogged filters. VW highly complex Diesel clean up, DPF, NOX trap, already reports of clogged DPFs. Think $$$$ when the VW exhaust system has to be replaced.

Further maintenance bonus on the Prius: Low break wear due to regen breaking.

The so called complexity is Solid state electronics/Battery/electric motor. All ultra reliable and maintenance free until you replace the battery (which have done 400 000 kms in taxis).

I still might consider a TDI, but I would buy new and sell before the warranty expired.

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If you want to selectively focus on certain aspects of the drive train the HSD could be seen as simple. But it's more than just the mechanical components. The complete system, mechanical and electronic, is complex.

I don't doubt that the cost of ownership is likely to be lower for a Prius compared to a 2009 VW TDI. Toyotas are quite reliable and low maintenance; my wife's RAV4 hasn't had one failure, except for a headlight bulb, in 100K miles. The Prius is no doubt an efficient and reliable machine. However, in my opinion the VW is a lot more fun to drive. If you're purchasing a car with only Consumer Reports guidelines then get the Prius. If you like good driving dynamics be sure to try other cars.

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A gas engine is more complex than a diesel engine...

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"A gas engine is more complex than a diesel engine..."

50 years ago. This isn't your grandpas diesel.

The gas engine here is a normally aspirated one. VS Ultra High pressure Direct Injected, Turbocharged Diesel with a Rube Goldberg exhaust clean up system.

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You would pay back your 5k much soon if you spent it on a prius.

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Steve, you must have used a defective napkin.

Because there isn't a $5,000 dollar difference between COMPARABLY EQUIPPED Jetta's with TDI and 2.5 cyl gas engines. The only way your napkin could have come up with a $5,000 dollar premium is if you compared a base Jetta S with no options, to the much more equipped Jetta TDI. By doing that, your napkin just forgot to account for over $5,000 dollars in features.

A better price comparison would be between the Jetta SEL (MSRP $22,965) to the Jetta TDI with the DSG-automatic and 17" avignon wheel options added (MSRP 22,270+options=$23,820). That equals an $855 dollar premium for buying a TDI with EXACTLY the same options and features as the same car with a gas engine.

Goto http://www.vw.com/jetta/compare/en/us/ to see the features, and then "build your own" for both the SEL and the TDI, and add DSG and 17" avignon wheels, and you should get the same numbers.

But the $855 premium doesn't even take into account the $1,300 dollar tax credit that the TDI qualifies for that the 2.5 gasser doesn't. You actually pay LESS for the TDI than the comparably equipped 2.5 gasser!

You pay less upfront, it has a higher top speed, faster 0-60, and it gets 9 to 11 more miles per gallon (cty/hwy). And if the last few years is any indicator, it will have a better resell value.

Considering all that, there really is only one question left --- where did you get those lousy napkins?

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