patrick.net

So can someone tell me, how a VW is better than a Pruis when it comes to fuel economy?
Smug factor... like a true Bay Aryan I can run my Golf TDI virtually free of fossil fuels (and therefore, with very little carbon emissions). Biodiesel aside, if you are really getting 50mpg on the highway, that is hard to beat. The diesel may beat you with long term maintenance costs (due to complexity of the multiple motor/generators on the Prius) but I don't think there is a definitive aswer yet. That said, TDI enthusiasts really enjoy their turbos.
If I went solar, I might be tempted by a plug-in conversion of a Prius.

The plug in hybrid is my conceptual model for the future. I have solar and may even change to peak shaving pricing when I get a plug in. I have a deposit and a place in line for the Aptera but that is looking like 2009 before I can get it. The plug in Prius is due out next year but really the specs for the electric range are still disappointing but better than nothing so maybe I'll just lease that while I'm waiting and then let my girlfriend drive it when our current lease is up on her Prius and hopefully my Aptera will be ready. I think we are going to find the next 3 years to be pretty exciting in the auto/renewable refueling industry.

My small solar company actually has a bit of a backlog of work so I really think times are changing for the better when in comes to renewables and reducing the need for foreign oil. It is getting rarer and rarer to find people who disagree with any substantive arguments.

I understand that they claim diesel is generally cleaner but I'm still not quite sure why it is preferrable over gasoline if the mileage is the same. I know they are making the engines cleaner but I don't see how something that makes visible smoke, and smells is cleaner than an efficient gasoline engine like a Prius.

Malcolm,

I don't think a gasoline Golf can beat a Prius on straight MPG. However, the new clean diesel Jetta might under some circumstances, and it should be quite close overall.The main thing about diesel engines is that they are fundamentally more efficient than gasoline engines. By "fundamental" I mean that it is directly attributable to the physics of the system.

The higher compression ratio of diesel engines is the main factor here.

I spoke recently with a retired MechE professor who was a bit of a diesel pioneer in his younger days, and has 40+ years of experience in the field, He explained to me the two main aspects of diesel efficiency. Number one is the higher compression ratio, which translates into more work getting done in the thermodynamic cycle.

When I was a kid my dad explained that the higher compression, slower combustion, and the nature of the fuel itself being a thicker kind of grade gave you more energy for the volume. This being the case, diesel hybrids should be even more interesting, and Aptera gets asked constantly why not use a diesel generator instead of a gasoline generator?

All that aside, I still don't know why the Golf is just granted the title of being superior to the Prius. Like I said, I've never driven one so I can't compare anything other than mileage, but that is the claim to fame that I keep hearing. So I am torn between the argument that diesel is just a better fuel than gasoline, or the argument against the Prius specifically, but no one can show me another gasoline powered car which is superior to the Prius for mileage and a reasonably good 4 cylinder car. I remember in the 80 and 90s the Chevy sprint that got very good mileage but was a 3 cylinder car, I would barely consider it a car given that my girlfriend had one and my brother and his friends used to play practical jokes on her by picking it up and moving it around.

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Malcolm,

I don’t think a gasoline Golf can beat a Prius on straight MPG. However, the new clean diesel Jetta might under some circumstances, and it should be quite close overall.The main thing about diesel engines is that they are fundamentally more efficient than gasoline engines. By “fundamental” I mean that the difference is directly attributable to the physics of the system.

I spoke recently with a retired MechE professor who was a bit of a diesel pioneer in his younger days, and has 40+ years of experience in the field, He explained to me the two main aspects of diesel efficiency. Number one is the higher compression ratio, which translates into more work getting done in each thermodynamic cycle, for the same amount of fuel burned.

The second aspect was new to me: A gasoline engine has a lower limit on the amount of fuel you can practically inject per combustion, because it gets impractically hard to ignite a "lean" mixture of gasoline and air. A diesel engine has no fundamental lower limit on the amount of fuel that can usefully be injected, because the ignition is thermal and distributed as opposed to central and by spark plug. This translates into a more efficient idle and low-load performance of the diesel.

But of course you cannot beat turning the engine off, which Prius is good at. Anyway, a diesel+ electric hybrid combines the best of both worlds, and when they arrive they will be truly awesome.

Justme, I'm referring specifically to a video on Youtube where the guy is saying the Golf diesel is superior. It is actually a funny video, but in my opinion is misinformative. Although it is the 1st generation which even I admit is hideous.

http://www.youtube.com/watch?v=oOvp69lnZbA

Malcom,

Yes, indeed the specific energy of diesel oil is also 11% higher than gasoline. Per wikipedia

"When burnt, diesel typically releases about 38.6 MJ/l (138700 Btu per US gallon), whereas gasoline releases 34.9 MJ/l (125000 Btu per US gallon), about 11% less.[2]"

This also helps, but it is the difference in thermodynamic performance which is the most significant aspect.

http://blog.wired.com/cars/2008/03/revealed-volksw.html

Admittedly this does look impressive. I don't see the price anywhere.

Yes, what you were saying about fuel air mixture made a lot of sense.

I would still have to be sold on the overall clenliness of diesel. I'm a hard sell, I remember going to places like Martinique where all the cars are diesel Mercedes and seeing a black layer of soot all over everything. I can't imagine that is good to breathe but I believe it will be a moot point which fuel is the backup. Having the primary drive train as electric is really the new technology which in my view seems certain to dominate in the near future. The explosion of hybrid acceptance has surprised even me. For those who don't live in California it is truly amazing to just look around a parking lot to see the proportion of hybrids to regular cars. I rarely even see SUVs anymore. On my last visit to SF, on some streets literally half the cars are Priuses.

The higher compression ratio of diesel engines is the main factor here.
And don't forget that the energy density of diesel fuel is about 10% greater than gasoline.
Malcolm, who is your utility company? Just curious to compare TOU rate schedules.

SDG&E

San Diego Gas and Electric.

Malcolm,

The video was funny but short on substance, except for the British class and the American testosterone :-).

The problem is that people watch it and then are all of sudden experts, so I find myself in situations where someone just quotes it and says, why not just get a Golf? To which I logically say why? And then they say, it's better. I'm not sure its even a fair comparison, logically one compares gas to gas diesel to diesel unless one wants to make the point that diesel is a better choice overall or the other way around. Funnily enough though, it seems like the Prius does in fact hold its own when compared to the straight diesel.

That condescending accent is really annoying to me. It's like he speaks that way to make up for a lack of substance.

It is funny how the English glorify the stereotypical redneck though.

Malcolm,

The 69.9MPG diesel+electric from your link is exactly the one I was referring to in my original post yesterday. What an awesome piece of machinery that is.

By the way, I have found another good source for VW TDI information:

www.tdiclub.com

There you can hang out and learn about the awesome mileage people have been getting from their older and not-so-clean diesels, as well as photos and news about the new Clean 2009 Jetta TDI.There are even photos of the demo models, same as the one I drove.yesterday. I took some photos, too, but no need to post hem when they are already available elsewhere :-)

Malcolm,

You know you're NOT a real redneck ..... if you need a British announcer and commentator to add legitimacy to shooting up a car with a caliber 0.50 machine gun. ;-)

Malcolm,

I don't see how people can just fashion themselves as experts on anything from watching taht video.

But there is an underlying point: Diesel is awesome, and now that it can be clean enough to be California legal, it will have a bright future.

Thanks Justme. I'm going to check it out. I guess that is the real develpment that I wasn't aware of that diesels weren't allowed in California. That clears a lot of things up for me because I always found myself at the root issue, if diesel is just plain better, why not just go that way and incorporate hybrid technologies with it?
Like I said, if my primary power is pure clean electric, and I'm only occasionally going to use a fuel backup, I don't think I really care whether it is an efficient gasoline engine/generator or a clean diesel one.

Malcolm,

Do you know anything about these electric cycles?

http://www.evcusa.com/

The performance they claim (acceleration and top speed) looks good. The range is tolerable for city use (75 miles max, but likely a bit less in practice). Cost to operate will undoubtedly be dominated by battery price and lifetime, as the cost of electricity per mile is tiny. How many charge/discharge cycles can one expect from lithium-ion batteries, or is there no way to generalize?

Thanks,

STCM

Funny, I thought the same thing about the redneck. I've never seen a poser wannabe redneck before. It would be funny if the guy is actually a branch manager at a B of A in Dallas.

It still is beyond me how some UCSD students could build a 80mpg diesel hybrid sportcar (several years ago) and the majors still can't get their act together. TDIclubdotcom has been great for dispensing advice on regular (and not so routine) maintenance (finally cleaned my snowscreen!), but they can be rather, uhhh, biased. Malcolm, you should head over there with your 50mpg claims and see how they react.

Malcolm,

I just re-read what you said about Martinique and old diesel. It is very true, just look at any US truck for the same problem. They need to fix truck engines and emissions as well.

I was down on the ground checking the exhaust on the 2009 Jetta TDI, and smoke and smell was absolutely undetectable. But I will admit I didn't inhale ;-)

Upshot: The new California-clean diesel engines, together with the ultra-low sulphur diesel which is now mandatory in 49 states, is the REAL deal. Alaska is joining in 2010,. Yee-ha.

I found also yesterday NYT article about another new diesel that is supposedly coming to 50 states later this year: The Honda Accord 2.2L clean turbodiesel! That could really put a dent in the overall car market. The competition is heating up, and there is more coming.

http://www.nytimes.com/2008/05/18/automobiles/autoreviews/18DRIVE.html?ref=autoreviews

They are claiming 53MPG highway on the test drive, "40MPG if I drove it like a Nascar Yahoo"/

Um, the article says SDSU. Just needed to clarify, I'm a little touchy on that.

If we all shift to diesel, granted in a hybrid form, but even so, would there be enough supply or would it send prices of diesel to $10 per gallon? It's already higher than gasoline where I live.

In that case, some people will shift away from diesel again, sending prices down. Market does wonders.

The Honda Accord 2.2L clean turbodiesel!

A four door vehicle of that size with that fuel economy would have a ready market with Taxi companies. I wonder if an Impala or Taurus will be introduced with similar technology.

Well, 53 is good but then again I actually have gotten close to that in a Prius. So I'm still not entirely sold unless diesel is actually say cleaner, or has some other social benefit like not supporting terrrorism.

Here is the video I put on Youtube to backup my mileage claim.

http://www.youtube.com/watch?v=C7vsIZj8GSc

EBGuy,

I agree, it is a sad state of affairs that GM, Ford and Chrysler have done so little of practical value when much of the technology just needed incremental improvements to become useful and 2x more efficient.

The reason is that energy efficiency ins un-cool and un-manly and does not fit into their testosterone-pandering marketing scheme. They will take short-term profit over doing the right thing ANY time. But look at the world of trouble they are in now. All the oil unnecessary wasted in the last 15 years makes me truly ill.

By the way, when I say "incremental" I do not mean to devalue the excellent effort that some automakers have put into clean diesel. It is incremental, but is far from easy, especially when you also have to be cost-effective. They have done an excellent job, and there is still more coming. Now people just need to buy them, and KEEP them when gas goes back to $3/gallon, which I suspect it will.

HeadSet, I think that is a real problem. The American car makers are now playing catchup because they grossly miscalculated what was going to happen. They are almost as incompetent as the bankers who inflated the housing bubble after being warned. I think what we will see is more small startups of American car makers like Aptera who will operate a lean manufacturing environment and unfortunately we will see the eventual demise of the big three.

The reason is that energy efficiency ins un-cool and un-manly and does not fit into their testosterone-pandering marketing scheme. They will take short-term profit over doing the right thing ANY time.

What are you talking about?

Energy efficiency is a matter of economy. Please do not attach ethical value to it.

All the oil unnecessary wasted in the last 15 years makes me truly ill.

The oil was paid for. Enough said.

Malcolm,

I agree, Prius is a great car. But the diesel does nearly as wellwithout the battery, and that is a BIG deal relative to cost and mass manufacturing. And as we saw, let us combine the two and get even better. I love the synergism of new engine technology and new hybrid+battery technology.

Diesel shortage and cost? There is no fundamental reason it should be like this. Just refine more diesel and less gas. Less work even for the refiners, they do not need the "cracker" units to break uop the heavy oil into gasoline-compatible molecule sizes. The current price differential has a lot to do with refining capacity and product mix, I'm pretty sure it is a solvable problem.

I think that image is changing quickly Justme. I don't know anyone who is saying that stuff anymore. It is mainly males who seem to think the new technologies are cool. Ironically it is the wives of people that I find to be the hardest sell when the topic comes up at a dinner. They love their Explorers and Excursions and as long as the guy is paying the gas bill they don't find the gas prices to be that inconvenient. In fact they wonder what all the fuss is about. :)

I need this answered before I will consider a hybrid vehicle:

1. What is the environmental cost of building the batteries
2. What is the environmental cost of recycling the batteries

I think I'm in agreement with you. I sure wouldn't bet against your prediction. All things being equal you could sell me on it. Like I said, as the secondary source of power I don't believe I really care what it is, I just want it to be clean.

Peter P,

You know damn well that "energy efficiency ins un-cool and un-manly" is not MY position. I find it to be very cool and very manly.

You can lecture all you want about "not attaching ethical value to economic matters". I don't care except to counteract the effect you may have on impressionable young children.

Peter, given the cost of ownership it is much lower to use batteries than buying gasoline the batteries clearly win environmentally. You build a battery, it does its thing, you have to constantly produce gasoline. That right there is a win for electric.

Recycling them is even better. When you research the subject I think you will find that the electrolyte has no environmental impact, and you can just reuse the casings.

The only argument that has any substance is the method of producing the electricity. It is a tradeoff, but I for one am on solar, and charging at night doesn't take any more capacity than daytime energy needs so to me it is a moot point. I put back what I would use by producing clean solar power for the grid during the day.

The Housing Bill is being blocked because of an alternative energy bill:

http://uk.reuters.com/article/marketsNewsUS/idUKN2547060320080625?pageNumber=2

Alternative energy is not OT after all. :)

Anyway, both bills are terrible.

Headset,

Taxicabs: I see a lot of Prius cars used for cabs around the world these days. But something bigger like and Accord Diesel or Taurus or IMpala could also make a dent in that market.

I'm worried, though, that Detroit is going to pervert the concept and build muscle-diesels much as they have built muscle-hybrid-SUV and the like of it. Detroit (and even Japan) has never seen a n ew technology that they can resist perverting into more testosterone.

Cabs are getting smaller. The good idling efficiency of diesel is also good for cabs, police cars and other service vehicles that end to idle extensively.