How can they improve the fuel economy of the next generation Pruis?

That could be one interpretation, but remember that VW is a diesel car company much more than a petrol car company. So despite putting most of their R&D money into diesel, it is no more reliable than their poor petrol relatives. Now look at a company like Toyota or Honda where the opposite is true. Compare the best petrol ICE companies to the best diesel companies, and diesel stinks.

Well, we already knew that.

 

That's it ? Your proof of excellent diesel reliability is the CR survey that shows it does not even reach average ? I wonder how many diesel owners have your reasoning disability.

 

If both gas and Diesel have the same repair record, it is the things the cars share that cause it while the things that are different, the gas and Diesel engines make no difference.

"It" was your proof that proved you wrong. I just helpfully pointed out to you that gas and Diesel versions of the same car had identical repair rates.

 

What about emission rating?

Marginally improved is the problem we are currently dealing with now, some call it "clean diesel". Others recognize it comes far short of a PZEV or SULEV rating.

 

There is synergy between gas and electric but not so much between diesel and electric. We need to keep that extra layer in mind so it is not as simple as comparing a single powertrain gas to diesel cars.

 

Well said, I think the hardest thing to do in a Hybrid is creating synergy between very small fuel efficient engine and electric motor - like Prius c.
Doing a hybrid from an engine that is inefficient at low power (a powerful engine) is way simpler to get big % improvements. There is a reason Peugeot didn't design a hybrid from 1.6 HDI engine, I bet that benefits would be minimal.

 

Actually, the MB E350 BlueTec comes very close to hitting SULEV (It even hits the SULEV NOx standard of 0.02 g/mile). It's just slightly higher than the SULEV NMHC limit (0.015 g/mile certified; 0.010 g/mile standard - http://www.arb.ca.gov/msprog/onroad/cert/pcldtmdv/2012/daimler_pc_a0030427_3d0_u2_diesel.pdf), which is the only thing keeping it from being SULEV.

Furthermore, gasoline has generally higher upstream ("well-to-pump") emissions than diesel fuel, which is one of the points I was trying to make in my previous post (#170). This is especially true of VOC. Here is a graphic of well-to-wheels (WTW) emissions of a PZEV-certified VW Passat 2.5 liter gasoline version compared to a Passat TDI (certified ULEV in California) based on EPA emission factors...





PTW = "pump-to-wheels" (i.e., the vehicular emissions)
WTP = "well-to-pump" (i.e., upstream emissions)
WTW = "well-to-wheels"

 

As far as how much benefit a diesel engine gets from "hybridization" compared to a gasoline engine, an Argonne National Laboratory study suggests that diesel actually gets more benefit from "hybridization" than a gasoline engine, but less from engine downsizing (http://www.transportation.anl.gov/pdfs/TA/89.pdf - "Conclusions" on slide #14).

The study is a bit dated, but perhaps it's still valid?

 

If I am reading the brochure correctly, the hybrid actually is the 1.6 HDI mated to the Peugeot hybrid drivetrain. As an interesting aside, these are 'electronically controlled manual' transmissions.

Using the same tyres, the 3008 hybrid emits 99 gr/km CO2, compared to 117 gr/km for the 3008 HDI.
This is the type of comparo PS should have been looking for. Hybridization of a GOOD diesel reduced fuel consumption by 15.4%, at an additional cost of about 10,000 USD in the UK before VAT.

 

I wonder if this well-to-pump is any differnet if refinery is producing 60% diesel and 40% petrol (case in Europe) or producing 40 % diesel and 60 % petrol (US?).

In Europe consumption of diesel is 70 % and gasoline only 30 % (can refinery even produce this values?), doing everything to get as much diesel yield from refinery (cracking) is definitely not environmentally friendly.
Doing things other way around is maybe a cause that EPA calculated "uglier" values for gasoline in US.

 

No, it's 2.0 HDI with 120 kW (163 HP)
3008 HYbrid4
go on the functioning tab

 

Right you are.

I picked the 1.6 option as the lowest CO2 emissions with about the same power (112 kw) ICE

 

The EPA emission factors are domestic emissions. Here's a reproduction of the upstream EPA emission factors table by stages (note the footnotes)...




The problem with gasoline (petrol) is that it's extremely volatile, something like 500 times as volatile as diesel fuel. Note the very high gasoline emission factor of VOC in the "Fuel Transport, Storage, and Distribution" stage relative to diesel fuel.

I haven't seen any emission factors for these products for Europe.

 

That is an easy question. Some of the european diesel is imported from America. Its less expensive shipping the distillate fractions, than cracking for a different mix. Refineries can produce any mix, but as they differ more from an ideal crack they become more expensive to produce. European refineries often operate on cleaner initial oil, lighter and sweeter. This lets them claim lower co2 emissions at the refinery,and equipment is less expensive . It also is what caused higher price spikes when Libya went off line, and will cause problems in the future. When talking about future vehicles, we should think of the heavier oils in well to pump exchanges. The heavy oils have more of a diesel crack. Natural gas energy is often used to remove sulfur, which may switch to more european diesel imports from the US and perhaps brazil, unless EU policies change. Brazil is building refineries to handle the lower quality, less expensive oils.

Removing sulfur at the refinery for ultra Low sulfur diesel greatly reduces the sulfur dioxide and particulate emissions. This takes energy at the refinery - well to pump- but actually makes diesel with pollution controls less expensive. SCR (specific catalytic reduction) drops down NOx pollution, without hurting fuel economy, but the converters add to the cost. That leaves NMOG emissions that can be handled in a traditional catalytic converter and particulate emissions. The particulate filters are immature, but quickly improving. But these two items urea and particulate filters add to maintenance costs versus gasoline engines.

Which brings us to the question, can diesel hybrids make sense versus gasoline hybrids in small cars like the prius or jetta. In my mind the answer is no. Toyota claims it can get gasoline direct injection turbo charged engines to 45% peak efficiency which is the efficiency as a vw tdi. It won't do this because it is more expensive, but it can get half way there to the low forties with di and small improvements. VW has a tsi (di turbo gasoline) that it is putting in its jetta hybrid. These vehicles will use more fuel than a diesel would, but efficiency would be almost the same, with the major difference the different energies in the fuels. That would mean you are paying more for not much efficiency gain. The only thing you really gain from the diesel is lower operating cost if diesel is cost is low enough to pay for the urea.

Get rid of the emissions equipment and diesel hybrids make perfect sense. Well to pump is more efficient because you can leave the sulfur in the fuel. No cost for SCR, urea, or particulate filters. In Europe lower standards may provide a short term advantage since peugot and volvo may be able to have lower pollution control costs, but euro emissions will get higher in the future. Diesel non-hybrids still do make energy sense, but as hybrid technology gets better, I would expect diesels to fade away from the mid size and smaller car market.

 

Agree with austingreen.

A report issued recently by DOE (EIA, “Light-Duty Diesel Vehicles: Market Issues and Potential Energy and Emissions Impacts.” January 2009, http://www.eia.gov/oiaf/servicerpt/lightduty/pdf/sroiaf%282009%2902.pdf), referenced a European study which demonstrated that, on average, refineries producing diesel emitted about one-half the CO2 emitted by refineries producing naphtha/gasoline streams (page 26).

 

Not according to EPA. I am looking at 34 MPG TDI vs. 33 MPG gas cars. Diesel upstream emission is 80 g/mi where gasoline is 66 g/mi (you'll have to change the dropdown box to show Tailpipe & upstream GHG).

 

I was actually referring to "conventional" emissions, not CO2.

However, if you notice in the link you provided, at the bottom of the page...

As I understand it, GREET assumes a certain portion of the gasoline sold is RFG, which has oxygenates (ethanol) added. Even though corn ethanol isn't a very efficient fuel, it does lower GHG emissions relative to pure gasoline somewhat. The upstream CO2 emissions calculated from the Toyota report in post #170 is pure gasoline, I believe. Plus, the energy input/GHG emissions likely keep changing, so it may not be completely accurate under the current scenario.

 

First thing to notice is the elantra, or the focus in my earlier example, uses less energy per mile makeing them more efficient than the vw tdi. Diesel has more energy per gallon. Therefore you would expect higher co2 emissions from the less efficient car. Making something a diesel doesn't automatically make it more efficient

I am unsure how they come up with those ghg emissions. With a crack of sweet crude, diesel should require less energy to produce, and I would suspect less ghg per gallon, but that graphic had more. Perhaps the US uses more high sulfur oil to produce its diesel and removing the sulfur produces more co2. Or maybe the figures are wrong The other eia has lower well to pump emissions. Maybe the gasoline is really e10. From wxman's previous post the refinery to pump VOC, which means NMOG + methane, from gasoline seems much higher than the VOC from diesel.


It doesn't really matter though, we would not expect a diesel hybrid to be much more efficient than a gasoline hybrid.

 

Another problem for diesel is that diesel has longer HC chains than gasoline so has a higher mass of carbon/BTU than gasoline.

 

Reduction in CO2 of 14% seems pretty good especially considering the Prius already low emissions.