Diesels challenge hybrids for fuel efficiency and desire.

I'm not so sure hybrid interest has waned possible bias out of Motor City?

Hope clean diesels come soon, but Japanese brands will probably be first and why not a diesel/hybrid?

 

In Baltimore, diesel cars would be no bargain. The diesel fuel costs about thirty cents per gallon more than regular gasoline. But diesel engines also cost more than gasoline engines also. So I don't see how the "break even" on fuel savings would ever occur.

I'd take a hybrid every time over diesel.

 

Hybrids also offer greater fuel economy but consumers have complained that the U.S. Environmental Protection Agency ratings overstate the mileage for some hybrids.

This is typical Detroit News BS. They know better. Why don't they ask all car owners what fuel economy they get, and how it compares with EPA numbers.

And if diesel cars are so wonderful, how come I can't buy one in New York?

Harry

 

I'm curious if you're looking in a bad spot, as GasBuddy's Baltimore site seems to show prices only about ten cents higher for diesel. But even if it was 30 cents, at current prices that's only a ten percent premium. The improvement in fuel economy for diesel versus gasoline in the same car with comparable power tends to run more than thirty percent, so you're still saving money per mile even if it costs more at each individual tank filling. Certainly, breakeven takes longer as diesel prices go up, but if you drive a lot or own the car a long time, it's still worth it.

Of course, that comparison works best if you're looking at a diesel Jetta versus a gas Jetta, for instance. It gets a lot murkier when comparing a hybrid or plain gasoline car that's already efficient to another which posts high numbers in diesel form but is only a middling performer economy-wise as a gasoline car. Gasoline and diesel fuel prices rise and fall at different times of the year and have different levels of price volatility. Gasoline tends to be highest in summer when everyone's driving, while diesel tends to be higher in the fall when people are buying up heating oil in preparation for winter. Gasoline fluctuates a lot throughout the year, while diesel doesn't jump around as much.

But hell, in 2006 when I got my car, the three most efficient cars available were the Prius, the Honda Civic Hybrid, and the Jetta TDI. I went with the Jetta since I wasn't really a fan of the styling on either the Prius or HCH. I prefer to be more subtle with the statements I make on the highway, so the Prius was out. I looked at the HCH a lot, but I wanted a folding rear seat. I also didn't want my twentysomething years to go away without a little bit of fun, and wanted a manual transmission. I sacrificed a few mpg to get what I wanted, and that bothers me a bit sometimes, but it's a nice car anyway.

Another thing to note is that less energy is required to refine diesel fuel compared to gasoline, so you effectively gain a few mpg before the fuel even gets to your tank. Then again, things get complicated here in Minnesota if you start considering the 10% ethanol and 2% biodiesel blends we have which change the energy picture a little, but I think diesel still comes out ahead. Ultimately I'd like to run on a high biodiesel fuel blend someday, and my choice of a diesel car was a hedge in that direction. However, even though Minnesota is a major biodiesel producer, it isn't as available as I'd like it to be and I've been worried about the quality of the stuff some folks try to pawn off as biofuel.

Blah, there I go writing a book again. Oh well, life gets complicated, doesn't it?

 

Putting a diesel engine in a hybrid is great, but it's going to bring up the price a bit more. Most people would probably pay the premium anyway, I know I would. Maybe they're scared to bring the price up any more than it already is? They're aiming at the economy car segment so they don't want to keep the car above $20K.

I like diesels, but if the new hybrids get better mpg than the them I'll stick with the hybrids.

 

Hey, I would be perfectly happy to see diesels competing for market share. While the engines are more expensive, the rest of the drivetrain is just as simple as any other car. That should make them pretty even in terms of manufacturing economics, no?

 

Sorry to be dogmatic here, but in 2006 the most fuel efficient car available was the Forgotten Car, the Honda Insight MT. Perhaps you were only considering 4-door sedans, but for accuracy...

I'm wondering how a diesel hybrid would be engineered. Gas engines generally make less torque low down than a diesel, and have HP on top. As I understand it, an electric motor has torque down low so in a gas hybrid this is used to add torque low down so that the gas engine can be optimized for efficient HP at higher revs. Basically the two complement each other. But diesels have grunt low down so what would one do? Is there a way to revise them for less low down torque and more top end HP, and if one did this would one sacrifice their FE? Doesn't seem like it would make sense to revise the electric system for more HP because then one would be running on electric all the time on cruise. One could turn the diesel into a generator, but then perhaps the conversion back and forth to electric would cost efficiency?

I suppose another way of saying it is that if you downsize the diesel so it has just enough hp for highway cruising, then you will probably have enough torque for acceleration so what will the electric motor do?

 

Huh, I guess you're right. But yeah, I was looking for a 4-door.

That might be a concern, but since most hybrids have CVTs these days, I'm not sure it's an issue. Besides, the motor has full torque at zero rpms. Diesels might have good low-end torque, but not that low.

Yes and no. A good mechanical transmission will have better efficiency than an alternator feeding power to a motor. On the other hand, diesel generators can have very high efficiencies, within spitting distance of some fuel cells, because they run at fairly constant speed and load.

 

I think that "enthusiasm" number - or how it is presented - is misleading. It says essentially seven percent fewer prospective buyers are considering a hybrid this year compared to last year. Here are some of the potential sources of that change:

1) The prospective buyers sampled for this year's study aren't the same as last year. Many of last year's 57 percent actually bought hybrids, shrinking the pool of those considering buying this year. As more people who consider buying a hybrid actually do buy one, the population of holdouts increases relative to those who would consider one.
2) The tax credit on Toyota's hybrids is almost gone. That will certainly diminish those looking at the most popular hybrid model.
3) While gas prices are higher this year leading one to think hybrids would be more appealing, the overall health of the economy isn't that good. Specifically, the housing market has hurt many folks in California and New England - exactly where hybrids sell the best. If people feel the pinch on mortgage payments they're not going to look at a premium-priced hybrid, especially one with lower tax incentives.
4) I can't find the text of the study but there's bound to be a margin of error of a few percent on those figures. Seven percent is not that much when you can whack a couple off for sampling error. The rest can easily be explained by the factors above.

--RN

 

I expect that some of the school of lemmings who wont buy a hybrid because it "cant" deliver EPA mileage may also be dissapointed with the FE performance of a diesel since it will also take some improved driving techninques to consistantly meet/beat its EPA FE.

 

No. For some reason, diesels have typically had accurate EPA numbers in the past, or the EPA figures have even been conservative. If you look at the "Your MPG" numbers at fueleconomy.gov for the Jetta or other diesels, they're typically outperforming the "revised" EPA numbers by 25%. The 2006 model was supposed to get 38 mpg combined. Under revised numbers which are supposed to make older cars more easily comparable to cars tested with the 2008 scheme, it's supposed to get 33 mpg combined. However, people are averaging around 41 mpg with it. I suppose the people who report mileage are more likely to drive for economy, but it's also a car that likes to go fast, so I suspect there are some leadfoots to even it out.

On the whole, I believe the 2007 and earlier tests that the EPA did were actually pretty accurate in the grand scheme of things. Individual car makes and models might have done better or worse in real life, but if you average everything out, they were doing pretty well. I got bored enough to do a spreadsheet and go through a few hundred cars in that database, and on average, real life drivers are outperforming the "new" numbers by 10%. Considering that numbers dropped 10-15% on most cars, the old ones were by and large more in line with what real people were seeing.