Volkswagen diesel car wins "Green Car of the Year"

The article pretty much explains it:

Awarded at the Los Angeles Auto Show by Green Car Journal (A trade magazine / Electric Cars, Hybrid Cars & More | Green Car)

Prius was not included as it is not new for 2009. The award is for new vehicles that "substantially raise the bar in environmental performance" and is "driven by Green Car Journal to allow experiencing driving dynamics first-hand" I suspect even if it was new the Prius wouldn't pass the driving dynamics part.

Green Car's Top 5 for 2009 are: BMW 335d, Ford Fusion Hybrid, Saturn Vue 2-Mode Hybrid, Smart ForTwo, VW Jetta TDI.

 

Anytime I see a diesel being lauded as a "green" vehicle, I point people to the emissions ratings. Sure, the latest diesels are a lot cleaner than a 1995 diesel, but they are MUCH dirtier than the best gasoline vehicles available.

The Jetta's air pollution score of 6 makes it 4X to 9X dirtier than vehicles with a 9.5 rating (depending on which pollutant you look at).


www.epa.gov/greenvehicles

 

FWIW, I did a pretty detailed comparison back when the new Jetta numbers came out. Much improved over the old ones, but still doesn't hold a candle to the Prius IMHO. Particularly when the '10s show up next spring.

http://priuschat.com/forums/prius-hybrid-news/49909-2009-vw-jetta-tdi-emissions-results-in.html

Rob

 

Is this a joke? No, it's just the establishment's resistance to change.

 

It's too bad the prius wasn't in the running. It's a waste of time to look at diesel unless paired with some hybrid system. It takes more oil to produce diesel, according to dr. andy frank. Isn't oil consumption in general just what we are trying to get away from? maybe some, not all of us. I hope everyone doesn't become fixated on the mpg's alone. chris

 

"Volkswagen's five-passenger Jetta TDI, which boasts a fuel efficiency of 41 miles per gallon..."
I'm not impressed. 41 ? That's revolutionary ? Am I missing something ? We give you a form of fuel that is more dense than conventional gasoline (therefore, it is expected that you would get more mpg than a gasoline vehicle BECAUSE you have compacted your fuel more dense (longer hydrocarbon chains), and all you manage is 41mpg ? FAIL!
(octane = 8 carbons. diesel fuel ranges from 10 to 15 carbon chains, averaging 12 carbons)
12 divided by 8 is 3/2, or 150%. My Corolla is EPA rated at 35mpg highway. (35mpg)(3/2)=52.5mpg! DO THE MATH !!!! This car is NO WHERE NEAR AS EFFICIENT AS A TOYOTA !!!! "Cogan said. "You get 30 percent better fuel efficiency, on average, with a diesel." -I'm glad to see we agree on the math. So does this mean that your car is not a diesel ? Or does it mean ... cough, cough ... the standard Jetta only gets 27mpg?

I find it curious that the Prius PHEV fleet vehicle did not win this award.

Volkswagen's U.S. chief, Stefan Jacoby: "It brings fuel consumption down, it's environmentally friendly, and -- this is a difference with a Prius -- this is really fun to drive." - Is he implying that the Prius is not fun to drive? That bastard !

I do have to say that the panel of judges are people that I have respect for.
With that considered ... I don't know what the heck they were thinking.

.

 

It's simple, it has to be new for MY 2009. The Prius PHEVs are MY2010 being released early. Not eligible.

It will when next year for 2010.

 

Rybold, diesel fuel contains on average 13-18% more energy per gallon than gasoline (depending on location and the time of year). Also, the Prius engine peaks at 35% efficiency, whereas most VW diesels are around 43% efficient (and the 3L TDi around 50% efficient).

 

So where is all the energy going when a high efficiency diesel gets so close to a Corolla consumption? Lets not forget the price of diesel too, and the cost to the community of ultra fine carbon particulates in the atmosphere.

 

Here in Europe, the diesel versions of equivalent gasoline-powered cars get on average 30-40% higher rated mpgs. It would be higher than this, but the diesel cars almost always have considerably heavier engines/transmissions than their gasoline counterparts (BMW being a notable exception).

A summary of gasoline vs diesel rated mpgs can be found here:

[Make, model] -- [gasoline mpg] -- [diesel mpg] -- [improvement]

Audi A4 ----------- 36 --- 51 --- 42 %
BMW 5-series ------ 31 --- 47 --- 52 %
Ford Fiesta ------- 47 --- 64 --- 36 %
Honda Accord ------ 38 --- 52 --- 37 %
Freelander -------- 27 --- 37 --- 37 %
Merc C-class ------ 38 --- 47 --- 24 %
Peugeot 206 ------- 45 --- 65 --- 44 %
Skoda Fabia ------- 47 --- 61 --- 30 %
Toyota Yaris ------ 50 --- 64 --- 28 %
Vauxhall Vectra --- 38 --- 49 --- 29 %
VW Golf ----------- 40 --- 53 --- 33 %

Official figures taken from Facts & Figures - Parker's (hence the UK gallons), choosing vehicles of the same body/spec but with equivalent performance.

 

Note that Prius ties for highest MPG, at 65.

.

 

No mention of NMOG's, PM10, PM2.5 in those EU fuel economy figures. To focus just on CO2 and ignore other emissions is a bit daft

 

Note further that it shows every gasoline powered vehicle a clean pair of heels in terms of mpg too

 

Clett, are these combined city/highway mpg results ?

Assuming they are, I'm not buying the 40 - 50% engine efficiency statement. If the higher density of diesel accounts for 15% of the higher mpg, then a diesel that has say 45% higher mpg than it's petrol cousin has an engine efficiency that is 145/115, or 26% better. A prius is easily 26% better than an ICE counterpart, but manages only 35% overall engine efficiency on a good day.

Another way to look at this is starting from diesel energy of about 40 kWh/ US gallon, and energy consumption of about 0.2 kWh/mile in non-aggresive driving. How many 90+ mpg (us) diesel cars have you seen ?

 

I see a lot of 50s and 60s on that list. Why are they
touting this 41mpg VW like it's something award-worthy ?

Check out the Yaris! Hot Diggity! Why didn't that car get the award ?
(actually the Peugeot 206 gets 65mpg!)
Let's couple that diesel Yaris with a Prius hybrid system, and get 90mpg!

 

do remember that these are imperial gallons (not US gallons). Thus multiply the European numbers by 0.8327 to get US mpg (65 imperial = 54 US).

Conversely, you can multiply the Jetta by 1.2009 to get imperial mileage (41*1.2009) = 49 mpg.

 

I had read that diesel was contained almost 20% more energy per gallon than regular gas. Moving a vehicle from Point A to Point B is pretty much a matter of physics and thermodynamics, with a number of variables to be sure, including engine efficiency, weight, aerodynamics, and rolling resistance.

Economics also enters in, however. Right now the price of regular locally is $1.79 per gallon. Diesel is $2.85. Thus, diesel which contains slightly less than 20% more energy per unit of volume is better than 50% more expensive. Even with the increased efficiency it doesn't add up to more economical. I'm keepin' my Prius.

 

Its also important to note that a 30% improvement in MPG is not the same as a 30% reduction in fuel usage, or fuel cost. This is why IMHO units of gal/100 mi or l/100km are a much more informative set of units than MPG. A 30% improvement in MPG is only a 23% reduction in fuel consumption, fuel costs, CO2 output, in other words most of the things people care about. Its also necessary to correct for the higher petroleum consumption and higher carbon content of diesel, just comparing mpgs doesn't tell that story either.

According to the EPA (fueleconomy.gov) it takes 1.1 gallons of oil to make a gallon of diesel vs. 0.96 gallons to make a gallon of gasoline. So a gallon of diesel takes 14.6% more oil to produce than gasoline. Similarly, for CO2 output the EPA uses a factor of 8788 g/gal for gasoline vs. 10084 g/gal for diesel. Thats a similar 14.7% more CO2 per gallon for diesel compared to gasoline. Converted to UK gallons, the kg/gal would be 10.55 for gas, and 12.10 for diesel. I've updated the table to include fuel consumption (gal/100mi), petroleum consumption (gal/100mi) and CO2 output (kg/100mi). The % columns are all the percent reduction for diesel over gas.

Make, model -- g mpg -- d mpg - mpg% - g gal - d gal - gal% - g oil - d oil - oil% - g CO2 - d CO2 - CO2%
Audi A4 -------- 36 ---- 51 --- 42% --- 2.78 - 1.96 -- 29% --- 2.67 - 2.16 -- 19% --- 29.3 - 23.8 -- 19%
BMW 5-series --- 31 ---- 47 --- 52% --- 3.23 - 2.12 -- 34% --- 3.10 - 2.33 -- 25% --- 34.1 - 25.7 -- 25%
Ford Fiesta ---- 47 ---- 64 --- 36% --- 2.13 - 1.56 -- 27% --- 2.04 - 1.72 -- 16% --- 22.4 - 18.8 -- 16%
Honda Accord --- 38 ---- 52 --- 37% --- 2.63 - 1.92 -- 27% --- 2.52 - 2.11 -- 16% --- 27.7 - 23.3 -- 16%
Freelander ----- 27 ---- 37 --- 37% --- 3.70 - 2.70 -- 27% --- 3.55 - 2.97 -- 16% --- 39.0 - 32.6 -- 16%
Merc C-class --- 38 ---- 47 --- 24% --- 2.63 - 2.13 -- 19% --- 2.52 - 2.34 -- 7.2% -- 27.7 - 25.7 -- 7.4%
Peugeot 206 ---- 45 ---- 65 --- 44% --- 2.22 - 1.54 -- 31% --- 2.13 - 1.69 -- 21% --- 23.4 - 18.6 -- 21%
Skoda Fabia ---- 47 ---- 61 --- 30% --- 2.13 - 1.64 -- 23% --- 2.04 - 1.80 -- 12% --- 22.4 - 19.8 -- 12%
Toyota Yaris --- 50 ---- 64 --- 28% --- 2.00 - 1.56 -- 22% --- 1.92 - 1.72 -- 10% --- 21.0 - 18.8 -- 10%
Vauxhall Vectra- 38 ---- 49 --- 29% --- 2.63 - 2.04 -- 22% --- 2.52 - 2.24 -- 11% --- 27.7 - 24.7 -- 11%
VW Golf -------- 40 ---- 53 --- 33% --- 2.50 - 1.89 -- 24% --- 2.40 - 2.08 -- 13% --- 26.4 - 22.9 -- 13%
Toyota Prius --- 65 ---- NA --- NA ---- 1.53 -- NA --- NA ---- 1.47 -- NA --- NA ---- 16.1 -- NA --- NA

So while the mpg improvement on these vehicles is 24-52%, the reduction in petroleum consumption and CO2 output is only 7-25%. Its also worth noting that the Prius, despite being in the middle of the pack in terms of size and acceleration, is overall the lowest in petroleum consumption and CO2 output. For both its ~15% better than the lowest diesels shown (Fiesta and Yaris).

So how does that compare to hybrids? We can do the same analysis on hybrids and their conventional gas counterparts, but it is complicated somewhat by the hybrid's affect on performance, and the lack of conventional versions of some. To try and equalize things, I'll compare the following cars, using the US numbers since their are a lot more hybrids available on the market.

- Prius Base vs. Matrix Base 1.8L Auto. Similar weight, Prius has longer wheel base, more leg/shoulder room, Matrix is a little taller, more headroom. Overall Matrix has more cargo volume, but Prius has more passenger volume by about same amount. 0-60 is about the same for both, ~10.5s.

- Camry 4cyl 0-60 time is ~8.9s, the V6 is ~ 6.5s, and the Hybrid comes in at 7.7s. Since this is exactly half way between the 4cyl and V6, it seems reasonable to split the difference on fuel consumption. That would give the theoretical 2.95L 5cyl Camry Auto an EPA combined 23.4mpg.

- The Civic Hybrid is a little slower than the 1.8L auto but otherwise very similar, so we'll just compare it to that.

- For the Escape, MT got the hybrid to 60 in 9.9s, actually faster than the 10.6 they measured for the V6. So in this case I'm comparing the hybrid 4 to the V6 auto.

- The Highlander comparison is pretty straight forward, as it has a slightly smaller V6 providing slightly better acceleration, though somewhat reduced payload/capacity.

- For the Tahoe hybrid, the 6L two mode gives no performance or payload/capacity advantage over the 5.3L conventional. In fact its worse both on both counts. We'll compare the Hybrid to the 5.3L XFE Auto, for both RWD and 4WD.

So same form as before, h for hybrid now replaces d for diesel, and US gallons now replace UK gallons. Consequently, you can't directly compare to the above without using 1.2 US gal = 1.0 UK gal, and even then differences in test procedures will cause discrepancies. The percent change numbers should be directly comparable though, since they represent a ratio. Since the fuel is the same, we expect roughly the same % change for each column (except mpg improvement) in this case.

Make, model -- g mpg -- h mpg - mpg% - g gal - h gal - gal% - g oil - h oil - oil% - g CO2 - h CO2 - CO2%
Prius/Matrix --- 28 ---- 46 --- 64% --- 3.57 - 2.17 -- 39% --- 3.42 - 2.08 -- 39% --- 31.4 - 19.1 -- 39%
Camry ---------- 23.4 -- 34 --- 45% --- 4.27 - 2.94 -- 31% --- 4.10 - 2.82 -- 31% --- 37.5 - 25.8 -- 31%
Civic ---------- 29 ---- 42 --- 45% --- 3.45 - 2.38 -- 31% --- 3.31 - 2.28 -- 31% --- 30.3 - 20.9 -- 31%
Escape --------- 20 ---- 32 --- 60% --- 5.00 - 3.13 -- 37% --- 4.80 - 3.00 -- 38% --- 43.9 - 27.5 -- 37%
Escape 4WD ----- 19 ---- 28 --- 47% --- 5.26 - 3.57 -- 32% --- 5.05 - 3.43 -- 32% --- 46.2 - 31.4 -- 32%
Highlander ----- 19 ---- 26 --- 37% --- 5.26 - 3.85 -- 27% --- 5.05 - 3.70 -- 27% --- 46.2 - 33.8 -- 27%
Tahoe ---------- 17 ---- 21 --- 24% --- 5.88 - 4.76 -- 19% --- 5.64 - 4.57 -- 19% --- 51.7 - 41.8 -- 19%
Tahoe 4WD ------ 16 ---- 20 --- 25% --- 6.25 - 5.00 -- 20% --- 6.00 - 4.80 -- 20% --- 54.9 - 43.9 -- 20%

For this dataset every hybrid listed except the Tahoes are more effective at reducing petroleum consumption and CO2 output than any of the diesels listed. In addition to being less effective, the diesels also generally have an emissions penalty, while the emissions of all the hybrids except the Tahoes are lower than their gasoline counterparts.

Lastly, relating back to the original topic, here are the numbers for the 2L Auto Jetta and the new TDI using both the EPA and VWs independent numbers. The EPA admits its current test seems to underestimate diesels by around 18% on average. That would still put it somewhat below VWs test numbers, so these two sets should create a range that will bracket the expected performance. These numbers are US data based in US gal, so they are directly comparable to the hybrid numbers above.

Make, model -- g mpg -- d mpg - mpg% - g gal - d gal - gal% - g oil - d oil - oil% - g CO2 - d CO2 - CO2%
VW Jetta EPA --- 25 ---- 33 --- 32% --- 4.00 - 3.03 -- 24% --- 3.84 - 3.33 -- 13% --- 35.1 - 30.6 -- 13%
VW Jetta Ind --- 25 ---- 40 --- 60% --- 4.00 - 2.50 -- 37% --- 3.84 - 2.75 -- 28% --- 35.1 - 25.2 -- 28%

So that puts the new Jetta's reduction of CO2 and petroleum consumption in the range of 13-28%. Thats not bad, but still not in the same league as the better hybrids, IMHO, which get better % reductions with an emissions improvement instead of the TDI's emissions penalty.

Rob

 

Its also interesting to note that the common argument that hybridizing large vehicles has more impact because they use more gas doesn't seem to play out in this data.

Gallons of Gas Saved over 100 miles by hybrid:
Escape --------- 1.87 gal
Escape 4WD ----- 1.69 gal
Highlander ----- 1.41 gal
Prius/Matrix --- 1.40 gal
Camry ---------- 1.33 gal
Tahoe 4WD ------ 1.25 gal
Tahoe ---------- 1.12 gal
Civic ---------- 1.07 gal

Rob