Yes "clean diesel" really is clean. (ACEEE.org)

[cwerdna]

The conspiracy theorist in me found this news article somewhat coincidental...
German automotive companies launch “clean-diesel” marketing campaign in US

Very interesting.... thanks!

 

[mrradon]

REF INFO:
Diesel Sulfur Content (PPM):
1994-2007: 500
2007-Present: 15
Particulate Matter (g/hp-hr):
1994-2007: 0.10
2007-Present: 0.01
Nitrogen Oxide (g/hp-hr):
1994-1998: 5.0
1998-2002: 4.0
2002-2007: 2.5
2007-2010: 1.2
2010-Present: 0.2

Well, a 90% reduction in particulates is a big improvement, but how do those particulate figures compare to, say, a Prius? Does a Prius emit any particulates? In other words, are we talking about clean (relative to ICE), or just cleaner than in the past?

These are the limits the engine has to stay within for EPA certification. The current medium and heavy duty engines we install actually are way below these limits. Particulate matter was typically around .005, the DPF cans are really good.
MAX Oxide was .015 (100,000 mile simulated load running test) DEF/SCR works extremely well.

In all new diesel emission technology makes them much better power sources then gasoline engines. Europe has proven that.

 

[cwerdna]

In all new diesel emission technology makes them much better power sources then gasoline engines. Europe has proven that.

Europe apparently has a tax structure (from what I understand) that makes diesel cheaper than gasoline, the opposite of the US most of the time. Fuel prices in Europe are FAR higher than the US, so people are more likely to gravitate towards high FE... and for whatever reason, it seems they're less likely to feel the "need" to buy battering ram of death class SUVs, for consumer/personal use.

As for "better", I can't see that at all. We've already shown that "clean diesels" aren't particularly clean, esp. compared w/a large # of far cleaner gasoline powered vehicles. And, if we look at CO2 output (which has nothing to do w/the EPA air pollution or smog scores) for given volume of fuel burned, it is higher since diesel has a higher carbon content (http://www1.eere.energy.gov/vehiclesandfuels/facts/2009_fotw576.html" onclick="window.open(this.href);return false.

Re: CO2 and GHGs, take a look at the # of tons per year in tailpipe CO2 or tailpipe & upstream GHG of these cars: http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=31767&id=31575&id=31585&id=32092&#tab2" onclick="window.open(this.href);return false; under the Energy and Environment tab.

 

[Stoaty]

Re: CO2 and GHGs, take a look at the # of tons per year in tailpipe CO2 or tailpipe & upstream GHG of these cars: http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=31767&id=31575&id=31585&id=32092&#tab2" onclick="window.open(this.href);return false; under the Energy and Environment tab.

That chart says it all:

 

[mrradon]

I see the fuel economy in the spec's as 30/42 for the Jetta TDI. I know for a fact last year my German Hertz rental Audi A3 got 50 city, 58 Hwy on a 3,500 km road trip (converted from l/100km).

I know for a fact my cousin's TDI Golf (two years ago) got about 55 for the trip to Gibraltar and back, with (2) wind surf boards and sails on top. (we weren't cruising +130kph).

I know a Prius would have gotten far far far less on this road trip, I've rented the darn things in CA and the leave lots left to be desired.

It has really nothing to do with the tax structure in Germany. Diesel has a lot higher energy per unit volume, but the government has realized with the Euro 5 emission standards the CO2 impact is much less using diesel. We would see the same here is fuel cost $8-10/gallon.

I'd have to look a the data you provided me in detail, but the CO2 from the tailpipe doesn't look quite right.

 

[Herm]

mrradon, those European trip examples that you mentioned benefited from lax pollution rules in Europe, once Euro VI comes into play you will see big economy hits. The other issue is that Americans dont tolerate cars that do 0-60 in 15 seconds, we will never get the economy that they get in Europe. A big advantage for economy is urea diesel exhaust fluid such as the new Passat uses, its inconvenient but not too expensive to refill the tank once in a while.

 

[cwerdna]

I see the fuel economy in the spec's as 30/42 for the Jetta TDI. I know for a fact last year my German Hertz rental Audi A3 got 50 city, 58 Hwy on a 3,500 km road trip (converted from l/100km).

I know for a fact my cousin's TDI Golf (two years ago) got about 55 for the trip to Gibraltar and back, with (2) wind surf boards and sails on top. (we weren't cruising +130kph).

I know a Prius would have gotten far far far less on this road trip, I've rented the darn things in CA and the leave lots left to be desired.

I wouldn't be surprised if some or all of these were going on: those cars have way less hp (and worse acceleration) than would be tolerated in the US (and thus wouldn't sell here), mis-conversion from l/100 km into miles per larger Imperial gallons, you were going slow and/or hypermiling, those cars would be illegal for sale in CA and possibly the rest of the US.

1 Imperial gallon = 1.20095 US gallons

50 miles per Imperial gallon = 41.63 miles per US gallon
58 miles per Imperial gallon = 48.3 miles per US gallon
55 miles per Imperial gallon = 45.8 miles per US gallon

(Google is a great unit calculator. Google for 55 miles per imperial gallon in miles per us gallon.

As for the EPA ratings, I've heard some claims (usually from diesel fanboys) that the EPA ratings tend to be lower than what many drivers see on diesels. It's possible since the EPA test doesn't measure actual fuel use anyway (for diesel and gasoline). They derive it from tailpipe emissions (see http://www.caranddriver.com/features/the-truth-about-epa-city-highway-mpg-estimates-measuring-fuel-economy-page-2" onclick="window.open(this.href);return false.

As for the inflated European mileage tests (vs. EPA ratings and "typical" actual), I mentioned 76.3 miles per Imperial gallon on the extra urban test for the Gen 3 Prius. That's 63.53 miles per US gallon.

http://www.caranddriver.com/features/the-truth-about-epa-city-highway-mpg-estimates-the-truth-about-epa-city-highway-mpg-estimates-page-3" onclick="window.open(this.href);return false; also briefly mentions them:

One last fuel-economy tidbit: Don’t even think of comparing EPA figures with stand­ardized fuel-economy tests from other countries because the test cycles are very different. For example, the European highway rating, called “extra urban,” is higher than the EPA’s by about 30 percent, so a rating on that cycle of, say, 60 mpg, would be closer to 40 in this country. The mainstream press, not realizing the difference, often complains that automakers refuse to bring efficient models here when, in fact, they may not be all that efficient when measured by U.S. standards.

For a given volume of fuel burned, burning diesel does emit more CO2 than burning gasoline. http://web.archive.org/web/20110203045034/http://www.epa.gov/otaq/climate/420f05001.htm" onclick="window.open(this.href);return false; has more details. But again, this has no relationship to the EPA smog/air pollution score.

As for Prius, well, here are some other FE tests. You can see where the TDI's fall vs. the Prius (regular one is the Prius Four there, they chose trim level/model Four) at http://www.consumerreports.org/cro/2012/02/the-most-fuel-efficient-cars/index.htm" onclick="window.open(this.href);return false;, http://www.edmunds.com/fuel-economy/fuel-sipper-smackdown-2.html" onclick="window.open(this.href);return false; and http://www.motortrend.com/roadtests/alternative/1010_2010_toyota_prius_iii_vs_2010_volkswagen_golf_tdi_dsg/viewall.html" onclick="window.open(this.href);return false;.

 

[cBeam]

cwerdna, I think you have some misconceptions about Diesel, maybe the following helps:

1) Any form of internal combustion engine is terrible inefficient, the reason is basic thermodynamics (look up "Carnot Cycle"). Most of the energy content used by ICEs is turned into unusable heat.
2) The same thermodynamics make a Diesel engine more efficient as compared to a similar gas (petrol) engine. Higher compression and higher usable (internal) temperature difference in Diesels are the reasons.
3) Diesel fuel contains more energy per unit as compared to gas (petrol) per unit.

Bottom line is that a Diesel engine will use less Diesel than a comparable gas engine uses gas (assuming that other conditions are comparable). You should let go of the issue that burning one unit of Diesel produces more CO2 than one unit of gas, this has only to do with the higher energy content of Diesel (wood produces less than half of CO2 when burned compared to gas or Diesel, I doubt you'd want to switch your gas engine to some kind of wood fired engine).

Please be aware that nowhere above I write about "clean". Wherever you burn fossil fuel it is not clean. And if burning Diesel or gas is cleaner depends on your definition of clean, and how engine manufacturer implement technologies to make exhaust less "dirty".

 

[cBeam]

If you want to compare efficiency of a Prius to a TDI, again it is a little more complex than meets the eye at first.

Looking at drivetrain efficiency of a car, I think we can agree that electric drivetrains are hugely superior to conventional drivetrains (be it gas or Diesel). The only reason why electric cars do not take off is that there is much more energy stored in one kg of fossil fuel than in one kg of battery.

If you drive a Prius over a long distance on a level road without accelerating and decelerating, the Prius' efficiency will be determined almost entirely by the efficiency of its gas engine. Under this (theoretical) condition the hybrid part of the Prius contributes nothing, on contrary. Assuming you have a low traffic highway where you can drive constant speeds over a long distance, this is where a TDI outperforms a Prius in real world driving in terms of efficiency.

However, if you have stop and go traffic like in cities or crowded roads, the measures implemented into a Hybrid pay off and outperform any kind of ICE. If you add a battery that is pre-charged (plug in hybrid, Volt with helper gas engine, or Leaf which gets rid of ICE altogether) then your efficiency goes up further.

Then again you can't drive a Leaf from Berlin to Gibraltar in any reasonable time today. Too much time would be spent to recharge the battery if you'd find recharging stations anyway. But you can drive a Prius or a TDI.

 

[cwerdna]

Bottom line is that a Diesel engine will use less Diesel than a comparable gas engine uses gas (assuming that other conditions are comparable). You should let go of the issue that burning one unit of Diesel produces more CO2 than one unit of gas, this has only to do with the higher energy content of Diesel

But, I've already pointed out to you numerous tests that the TDI vehicles available in the US get worse mileage than the Prius. Even if they got equal mileage, the diesel would still emit more CO2.

Please be aware that nowhere above I write about "clean". Wherever you burn fossil fuel it is not clean. And if burning Diesel or gas is cleaner depends on your definition of clean, and how engine manufacturer implement technologies to make exhaust less "dirty".

We've already established that "clean diesels" do worse on EPA air pollution/smog scores. And, in test results, some pollutants are an order of magnitude higher the Prius.

If you want to compare efficiency of a Prius to a TDI, again it is a little more complex than meets the eye at first.
...
If you drive a Prius over a long distance on a level road without accelerating and decelerating, the Prius' efficiency will be determined almost entirely by the efficiency of its gas engine. Under this (theoretical) condition the hybrid part of the Prius contributes nothing, on contrary. Assuming you have a low traffic highway where you can drive constant speeds over a long distance, this is where a TDI outperforms a Prius in real world driving in terms of efficiency.

We've already established that this isn't the case either. CR's highway test (last page of http://www.consumersunion.org/Oct_CR_Fuel_Economy.pdf" onclick="window.open(this.href);return false is run at a constant 65 mph. The Prius achieved 55 mpg. The TDIs achieve 45 to 51 mpg on that test, depending on the car and transmission.

In http://www.edmunds.com/fuel-economy/fuel-sipper-smackdown-2.html" onclick="window.open(this.href);return false;, they mention "The final portion was the highway jaunt from Las Vegas back to San Bernardino on Interstate 15." which is 221 miles per Google Maps. The Prius beat the Jetta TDI by 6.8 mpg.

In another test, comparing previous gens of vehicles at http://www.caranddriver.com/comparisons/honda-civic-hybrid-vs-toyota-echo-vw-jetta-gls-tdi-toyota-prius-comparison-tests" onclick="window.open(this.href);return false;:

For highway mileage we drove freeways across Michigan from Ann Arbor to Holland and back, 337 miles between fills. Traffic hustles along these days. We drove 75 to 80 mph where possible, at the upper range of flow.

On their above highway test, the Prius hit 50 mpg while the TDI got 42 mpg.

Hybrid Synergy Drive hybrids and many other hybrids get increased ICE efficiency due to them using the Atkinson cycle (http://auto.howstuffworks.com/atkinson-cycle-engine3.htm" onclick="window.open(this.href);return false.

 

[cBeam]

cwerdna, here are the latest fuel consumption numbers (first number is city, followed by out of city (highway), third is a combined value)


Golf TDI (77 kW) 4.6 / 3.3 / 3.8 l/100km
Prius (73 kW) 4.0 / 3.8 / 4.0 l/100km

For both brands these are self reported numbers derived from a mandatory test cycle. Real life consumption numbers are worse, however each manufacturer for sure did his best to come up with the best possible consumption numbers.

Looking at these numbers is becomes evident what I tried to explain to you earlier: A well designed hybrid performs very well in city traffic or traffic with frequent acceleration and deceleration. Driven on highways with constant speed the electric part of the hybrid does not contribute any more, and consumption is only dependent on the ICE. This is where the Prius burns 3.8 l/100 km, while the TDI uses 3.3 l/100km (about 15% less). This establishes that a TDI uses less fuel than a Prius when driven over long distances with constant speed.

I am not sure if you can buy the Golf TDI in the US, for sure you can buy the Golf TDI or the Prius in Germany.

I guess your confusion stems that you try to compare apple to oranges. All things equal a modern Diesel engine is more efficient than a modern gas (Petrol) engine. This is what I tried to explain to you. Can we establish that? It's basic physics, nothing else: Carnot Cycle.

A car is as efficient as the sum of its part. If you put the Prius Synergy Drive into a Hummer, the efficiency of the "car" will go south, in the city because of the weight, and on the highway mainly because of the wind resistance of the Hummer. In this case a 20 year old BMW will consume less fuel than the Hybrid Hummer.

And back to "Clean": If you use EPA's definition of clean, then you have the numbers. If you use a different definition you will compare different numbers. If you compare a clean ICE to the tailpipe emissions of an electric car, you will agree that the cleanest ICE does not look that clean anymore.

 

[DaveEV]

Screw test cycles or theoretical efficiencies. Let's look at real world results. Isn't that all that matters in the end?

If I go to fuelly.com I can easily look up self=reported fuel economy numbers.

And shock - those numbers are very close to the EPA numbers.

2012 Jetta/Golf TDI: Average slightly under 40 mpg.
2012 Prius: Average slightly under 50 mpg.

 

[downeykp]

In this scenario the diesel should get better highway mileage. But who does all of their driving on the highway. If you are talking about driving the family to Disneyland the TDI should get better mileage, but which is more economical to drive to Disneyland? The price of diesel makes it bad economically even getting better highway mileage. This does not even take into consideration a Prius is a hell of a lot more comfortable car to drive in and is less polluting.
In real world commuting the diesel can't really compare because of the start and stop nature of commuting.

cwerdna, here are the latest fuel consumption numbers (first number is city, followed by out of city (highway), third is a combined value)


Golf TDI (77 kW) 4.6 / 3.3 / 3.8 l/100km
Prius (73 kW) 4.0 / 3.8 / 4.0 l/100km

For both brands these are self reported numbers derived from a mandatory test cycle. Real life consumption numbers are worse, however each manufacturer for sure did his best to come up with the best possible consumption numbers.

Looking at these numbers is becomes evident what I tried to explain to you earlier: A well designed hybrid performs very well in city traffic or traffic with frequent acceleration and deceleration. Driven on highways with constant speed the electric part of the hybrid does not contribute any more, and consumption is only dependent on the ICE. This is where the Prius burns 3.8 l/100 km, while the TDI uses 3.3 l/100km (about 15% less). This establishes that a TDI uses less fuel than a Prius when driven over long distances with constant speed.

I am not sure if you can buy the Golf TDI in the US, for sure you can buy the Golf TDI or the Prius in Germany.

I guess your confusion stems that you try to compare apple to oranges. All things equal a modern Diesel engine is more efficient than a modern gas (Petrol) engine. This is what I tried to explain to you. Can we establish that? It's basic physics, nothing else: Carnot Cycle.

A car is as efficient as the sum of its part. If you put the Prius Synergy Drive into a Hummer, the efficiency of the "car" will go south, in the city because of the weight, and on the highway mainly because of the wind resistance of the Hummer. In this case a 20 year old BMW will consume less fuel than the Hybrid Hummer.

And back to "Clean": If you use EPA's definition of clean, then you have the numbers. If you use a different definition you will compare different numbers. If you compare a clean ICE to the tailpipe emissions of an electric car, you will agree that the cleanest ICE does not look that clean anymore.

 

[cwerdna]

cwerdna, here are the latest fuel consumption numbers (first number is city, followed by out of city (highway), third is a combined value)

Golf TDI (77 kW) 4.6 / 3.3 / 3.8 l/100km
Prius (73 kW) 4.0 / 3.8 / 4.0 l/100km

For both brands these are self reported numbers derived from a mandatory test cycle. Real life consumption numbers are worse, however each manufacturer for sure did his best to come up with the best possible consumption numbers.

Looking at these numbers is becomes evident what I tried to explain to you earlier: A well designed hybrid performs very well in city traffic or traffic with frequent acceleration and deceleration. Driven on highways with constant speed the electric part of the hybrid does not contribute any more, and consumption is only dependent on the ICE. This is where the Prius burns 3.8 l/100 km, while the TDI uses 3.3 l/100km (about 15% less). This establishes that a TDI uses less fuel than a Prius when driven over long distances with constant speed.
I am not sure if you can buy the Golf TDI in the US, for sure you can buy the Golf TDI or the Prius in Germany.

Source of these numbers? You can buy a Golf TDI in the US but not w/only 77 kW (103 hp). The ones here are 140 hp (http://www.vw.com/en/models/golf/trims-specs.html" onclick="window.open(this.href);return false. This goes back to Herm's statement about acceleration and mine.

Your figure about the Prius having 73 kW is wrong. Net system power is 134 hp (100 kW), see http://www.toyota.com/prius-hybrid/specs.html" onclick="window.open(this.href);return false;.

And, the Golf here per http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=31576&id=31767" onclick="window.open(this.href);return false; is rated at 42 mpg highway vs. the 48 mpg highway Prius, not to mention 34 mpg combined vs. 50 mpg combined. And, BTW, the Golf is EPA rated as a compact vs. the midsized Prius (under Specs tab).

Oh yeah, and again, CA/CARB spec vehicles of each yield 6/10 on the EPA smog score for the TDI vs. 9 for the Prius.

Again, I've already pointed out to you FOUR separate tests where on the same route/course besides the EPA's (not done on a road anyway), the Prius outperformed the VW TDI on highway mileage. I'm sure I can find more.

Back to CR's results, notice which non-plugin vehicle has the highest highway result at http://www.consumerreports.org/cro/2012/05/best-city-highway-mpg/index.htm" onclick="window.open(this.href);return false;?

I guess your confusion stems that you try to compare apple to oranges. All things equal a modern Diesel engine is more efficient than a modern gas (Petrol) engine. This is what I tried to explain to you. Can we establish that? It's basic physics, nothing else: Carnot Cycle.

Yes, diesels are generally more efficient and use less fuel than non-hybrid gasoline powered vehicles.

 

[Herm]

Hybrid Synergy Drive hybrids and many other hybrids get increased ICE efficiency due to them using the Atkinson cycle .

The Prius engine has been tested at a 38% efficiency level.. that is nearly diesel like.. and Toyota is promising 42% in the near future.

 

[DaveinOlyWA]

I kinda lost count but think we on our 3rd or 4th lap in this discussion, so lets put in something new. what difference does a point or two make on the particulate rating?

It is the very finest soot – so small that it lodges deep within the lungs and from there enters the bloodstream – that contributes to most of the public health toll of air pollution including mortality. Diesel soot, which is also a carcinogen, is a major problem because it is concentrated in cities along transportation corridors impacting densely populated areas. It is thought to contribute to half the premature deaths from air pollution in urban centers. For example one in six people in the U.S. live near a diesel pollution hot spot like a rail yard, port terminal or freeway.

http://www.treehugger.com/environmental-policy/air-pollution-responsible-3-million-premature-deaths-year.html" onclick="window.open(this.href);return false;

are diesels cleaner? yes.

are they clean enough? no way

 

[theaveng]

For all the talk of TDIs "only" getting a 6 on the smog score..... the Chevy Volt hybrid also gets "only" a 6. And most on this forum would consider that a clean car. They are identical because they are both ULEV cars. IMHO gasoline cars should be required to have soot filters too. Their PMs are much smaller but they are there.

This does not even take into consideration a Prius is a hell of a lot more comfortable car to drive in and is less polluting.

Yes the Prius is SULEV. Even non-hybrids are SULEV, just by adjusting their tuning to run richer and emit less NOx. It's isn't that difficult.

BTW if anybody cares, there an Insight TDI in the wild.

That's right: Diesel-electric hybrid. The owner has been able to get over 100 MPG thanks to its teeny-tiny 1.2 liter engine (about 90hp). Which is what you expect from ANY high-compression engine whether it's gasoline or diesel: Better efficiency. (That's why the Volt uses a high compression engine.) The diesel provides the fuel savings and the electric provides +10 extra horespower for clmbing hills or faster 0-60 acceleration.

 

[cwerdna]

For all the talk of TDIs "only" getting a 6 on the smog score..... the Chevy Volt hybrid also gets "only" a 6. And most on this forum would consider that a clean car.

If you buy a newer CA spec '12+ Volt, it gets a 9 on the smog score. See http://www.fueleconomy.gov/feg/Find.do?action=sbs&id=31618&id=32655&#tab2" onclick="window.open(this.href);return false; and http://green.autoblog.com/2011/11/16/new-enhat-pzev-chevy-volt-ready-for-california-hov-access-extra/" onclick="window.open(this.href);return false;.

You need this cleaner version in order to get CA green HOV stickers. I seriously doubt that GM would sell and produce any of the dirtier versions for CA or CARB states now. It would be stupid.

The Volts prior to this enhAT-PZEV version were ineligible for CA HOV stickers due to emissions and battery warranty.

 

[theaveng]

As I've mentioned before a VW diesel could get a PZEV rating too (that's a 9 on EPA's smog scale) without barely trying. Run the engine richer and the NOx drops the 0.5 g/mile needed to get the CARB certification. It isn't difficult. It's how Ford got their diesel Focus to meet PZEV standards.


Final thought: While EVs are obvioualy cleaner (except anywhere east of the rockies where electricity is made from coal) (then they are dirtier than a prius), they will never be able to fit my lifestlye where I hop in a car and drive 500 milesto visit my parents (just for the hell of it). An EV would run-out-of-energy before it got even halfway through that trip. HYBRIDs are the future that 99.99% of Americans will choose as the only real, true practical replacement for pure gasoline cars, because they can be recharged in 5 minutes instead of 500.

Trying to maek me feel GUILTY because I drive a hybrid? "Oh you dirty filthy polluter." Well you can take that attitude and shove it the same place I told the Christians to shove their bible when they kept pounding on my door: Judgmental hateful people always saying "You are going to hel you filthy sinner!" You EV drivers act the same way with your "you are a filthy hybrid driving polluting earth-killing sinner!"
Your hate drives people away from even considering EVs.

 

[cwerdna]

As I've mentioned before a VW diesel could get a PZEV rating too (that's a 9 on EPA's smog scale) without barely trying. Run the engine richer and the NOx drops the 0.5 g/mile needed to get the CARB certification. It isn't difficult. It's how Ford got their diesel Focus to meet PZEV standards.

Then why don't they esp. if can be done "without barely trying"? Re: diesel Focus meeting PZEV standards, source? I see no diesel Focus being sold in the Us at all.