New VW Diesel Could Match Hybrid Mileage

being a "convert" to hybrid (my 1st ever!) after owning vw tdi for almost 10+ years, I can appreciate this!

 

Mike,

Wayne did post a graphic for the 1.6L Ford Fusion Ecoboost...



Ford February 2013 Sales up 9.3% + 2013 Fusion SE Review - CleanMPG Forums (Post #1)

He notes that the mileage may be 3 mpg low, but even taking that into account, the Passat TDI has about 50% higher fuel mileage than the Fusion at those cruising speeds.

Edmunds achieved almost 52 mpg at 70 mph with a Passat TDI DSG in the highway test they did last year...

The 40-MPG Challenge

 

Don't get trapped by thinking 1 mpg has a fixed value. In terms of consumption (L/100km), the difference between the Passat and Prius is greater at 70mph than 50mph.

50mph L/100km:
Passat: 3.4
Prius: 3.6
Difference = 0.2L/100km

70mph L/100km:
Passat: 4.88
Prius: 5.16
Difference = 0.28L/100km

Going by mpg is not a good way to measure consumption. The Prius is also more aerodynamic than the Passat. The Passat is fighting an increasingly large difference in drag compared

 

First I said jetta, and the graphs are for the passat. There isn't a inconsistancy. The graphs don't go out far enough for the knee in the prius curve. The passat should be compared to the camry hybrid cures. My claims were diesel versus atkinson, and talked about hybrids not getting their varried speed bursts at higher speeds. Cruise control isn't the best test of a hybrid. We all know the prius is more aerodynamic than the compared cars, which should help its curves. We see this. The diesel energy premium is in % compared to gasoline, not in mpg. If you have lower efficiency, you need fewer mpg differencial to make up for it.

I would definitely trust bob's tests, but they use different methodology. If he were to test a jetta tdi I would think he would also get higher than clean mpgs methodology. I trust wayne in testing cars in the same way. We should not compare apples and oranges.

 

As I was passing by the closest-to-my-house gas station today, I noted a 50 cents difference in the fuels used by a Prius and a Diesel Jetta or Passat. $3.899 versus $3.399

So lets talk miles per dollar since that is what the consumer feels at the pump. How do the two compare on that scale?

 

You will not be able to find ONE_RIGHT_ANSWER because the price difference between diesel and petrol vary across the country as does the highway:city use between car owners.

I can show you how it pens out for my wife as an example:
She drives 50% highway, 50% city
Say the diesel car is 45 mpg highway, 35 mpg city
The Prius is 49 mpg highway, 51 mpg city
Petrol is $3.30 a gallon, diesel is $3.70

The mpg is correctly calculated as a harmonic mean, but I'm feeling lazy and will just take the average... (this will be to the diesel's advantage)
The diesel would be (45+35)/2 = 40 mpg
The Prius would be 50 mpg

Diesel pennies/mile fuel cost is 370/40
Prius pennies/mile fuel cost is 330/50

 

I swear those are your charts showing MPG, it is not like I introduced them. Similarly, this is PriusChat, of course we will compare other cars to Prius. Had you wanted to compare to different cars, this may be the wrong forum.

I am not anti-diesel, I am not even anti VW, but fussing that I used charts you brought to the discussion in a way you dislike is pretty silly, if you can do the math to make charts that show the points you want them to show, I would use those graphs instead.

(I once made this graph showing how rarely I make graphs:
)

 

They aren't my charts. They are made by Wayne Gerdes at CleanMPG. I was hoping it would be clear enough for people without me needing to re-plot everything. Here is a table for you though.

L/100km

Code:

Speed Prius Passat  Difference
50	3.60	3.53	0.07
55	3.78	3.72	0.07
60	4.06	3.98	0.08
65	4.50	4.35	0.15
70	5.16	4.88	0.29

If you don't like L/100km then you can simply do some math on the charts. At 50mph the Passat gets 2% higher mpg, but at 70mph, the Passat gets 5.9% higher mpg. Again, since 1 mpg does not have a fixed value, it can sometimes be confusing to use those units. The point I want to show is that the Passat does become increasingly more efficient relative to the Prius at higher speeds, hopefully I have done that now.

 

These numbers look quite believable. If CO2/mile was calculated the Passat would break even at about 65 mph and win at 70 mph. Is there really any argument that the Passat is a match to the Prius on the highway ? The point we keep making that the diesel propaganda press ignore is the urban cycle.

 

Like others in the thread, I am not a diesel hater, I even go as far to recommend another colleague to get a diesel if the travel is mainly highway. But admittedly I am a bit of a VW hater because of the flaks I cop from my ignorant VW loving work colleague, also I would not recommending any VW because of the potential unreliability issues like others have mentioned in this thread.

However, diesel prices are a little dearer than petrol in Australia, so all the so-called diesel advantage (@ a mere 5.9%) quickly vanished at the pump before you drive.

 

Why did you mix MPH with L/100KM?

There are not any places in Australia where you could do 70mph (or 112kmh) anyway, maybe travelling to interstates or something.

 

An unfortunate result of his Canadian origins I presume.
The French and British never reached an understanding.

 

And diesel is $4.20 gallon here

cm_tenderloin ? 2

 

"Here" would mean so much more if you filled out the Location in your Profile.

 

Diesel car emits less particulates than the Prius, yeah, right.

DBCassidy

 

Jimbo was asking at what point the diesel becomes more frugal, I am providing data to answer his questions.

Also, I figured even fewer people use gal/100mi than l/100km.

 

Then the question remains, why are you not including urban numbers too ?

 

Correct. I am the one wjo was trying to get numbers to back up the claim that the faster you drive, the better diesels are. I estimate 10 % of my driving at 44 MPH or lower, 10% at more than 65, and 80% between 45 and 65. Some one who uses freeways more than I do may indeed do better in a Diesel.

And yes I pressured Seftonm into using fuel per distance when he objected to me using the MPG graphs he presented. He could have converted round MPH to odd Kph, but no one would have been helped.

 

I didn't see anybody asking for them, and even if they did ask for them, I don't have any numbers to give them.