One problem with diesel right now (in the US) is that it costs a lot more than regular gas ($2.49 versis $1.99/gal around here). So a car whose gas version gets 50mpg would have to get 62mpg as a diesel to break even in fuel costs. I suspect some of the increased cost we are seeing is the result the costs of tooling up to produce low sulfur diesel (just like unleaded gas was more expensive than regular when it first came out).
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We saw the same thing out here when we switched from MTBE to ethanol and they had to clean out all the tanks. For example, the first spike is associated with hurricane Katrina, and I'm guessing the second is associated with the switch. The thing with diesel, is that the consumer gets ~14-18% more energy per gallon because it has a higher BTU rating and the EPA takes this into account when doing FE testing, so the consumer who buys a diesel that gets 45mpg combined would see the equivalent of ~53mpg real world. I wouldn't be surpised if diesel and gasoline prices stabilized such that this disparity in energy was reflected in price, but I doubt this will happen because the majority of diesel use is OTR rigs, and industry likes to keep the bottom line on the low side.
Going on to diesel FE, something else that's a big confound is the use of high drag autos w/o LRR tires. Supposedly, a big wing and LRR tires on a TDI Beetle result in ~60mpg EPA highway, a ~23% increase. Toss a TDI in an Insight shell, and we'd probably see ~80-90mpg EPA highway, and well over 100mpg real world, with the cruise control set at ~50-55mph. One of VW's 3-cylinder 1.2L engines, as seen in the 3L Lupo would probably see ~120mpg@55mph in an Insight with a m/t. Quote:
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An Insight is essentially the same thing as a 3L Lupo which gets ~80USmpg, they both weigh ~2k lbs, the biggest difference is in aerodynamics (Insight's better iirc) and transmission. The 3l Lupo has some wonky transmission that always makes sure the engine is operating as efficiently as possible, so that everyone who drives the cars according to the Euro driving schedule gets the listed mileage. I'm also betting this tranny has a few more losses than a standard, but still is better than how most people drive. So, I'm guessing that the slightly larger/less efficient 1.9L tdi with an m/t could see the same EPA that the 3L lupo does, and better with the more efficient 1.2L tdi and m/t.
Here's a blurb about the 3L's trip around the world, something like 95-100USmpg with a 50-55mph average speed, all in a vehicle that weighs the same, has a greater Cd (.29 versus .25), probably greater reference area, and I'm guessing slightly worse transmission in terms of losses. Here's where they mention speed. Quote:
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Sry for highjacking the thread. Heres a pick thats close to the F150 wheels. Only different centercaps.
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Altering Stance
Well, last night I did some calculations regarding the Prius vs. the Honda Diesel.
In Honda's case, they're limited to the 2.2, which will fit in the Civic, and drop right in the Accord, but probably not the Fit. Emissions: depending on fuel. Probably will be at least B50 compatible, which should reduce emissions. Power-to-Weight: Prius curb weight = 2930 lb. Combined HP = 110 hp. P/W Ratio = 0.0375 Projected curb weight of Accord with Diesel: Euro Accord Diesel 6MT (USDM TSX = 1477kg = 3256 lb). Acura TSX 6MT = 3257 lb. One pound heavier. The U.S. Accord 5MT with the K24 (TSX engine) weighs 3133 lb. + 1 lb. = 3144. 2.2iCDTi HP = 140 hp P/W Ratio = 0.0445 The Honda will have more power-to-weight by 15.7% FE for the Prius: 60/51/55 Projected Accord Diesel: 32/53/42 CO Emissions (g/km) Prius: 104 Accord: 145 Welp, it looks like the Prius wins for better emissions and FE , with the Accord yielding a slightly better highway FE rating. Hypermilers should choose the Prius, and the general public perhaps the Diesel, as the EPA FE may be easier to achieve for the average lead-footed user -- introduce Bio-Diesel and less petroleum is used, which could outweigh the FE disparity in emissions. So short answer, it would be tough. Crap, I just talked myself out of a Diesel and into a Hybrid -- better yet, a Diesel-Hybrid! RH77 |
If only the Opel Eco Speedster would be produced(97 mpg, 160 mph top speed). Then I'd actually be interested in buying a car, instead of re-engineering one that is nearly 40 years old.
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So True...
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Correct me if I'm wrong, but has the Opel Speedster been transformed into the Saturn Sky roadster for the U.S.? If so, the idea is possible -- but sport and economy is too polar right now, especially for General Martyrs. IMHO, once the masses migrate from "go-fast" to "FE+", the sport factor is lost. RH77 |
I found something very interesting about the diesel Accord.
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<rant> The one thing that's really irritating is the EPA's over the top emissions mandates. The let manufacturers of large pickup trucks go balls out with NOx emissions compared to the EU (we have a max .93g/km and they have a max of .39g/km). We don't have as stringent CO emissions, and compared to them, out small car NOx regulations are draconian. Taking into account the difference in engine type, they have allowed roughly twice as many HC emissions for gassers compared to diesels, and roughly twice as many NOx emissions for diesels compared to gassers. Because diesels tend to make more NOx and gassers more HCs. We'll ignore the concept that HCs are actually carcinogens, and while NOx is bad (smog/acid rain), it's not a carcinogen, and even more importantly, diesel doesn't evaporate at the gas station like gasoline. So when refueling, carcinogenic HC emissions are even greater for gassers, which they should include, but don't seem to (need to google this). It's just... yeah, and I have a feeling it's a kickback to the trucking/auto industry to a certain extent... <end rant> edit- EPA, EU. |
By that I mean in gassers the throttling of the engine results in a difference in pressure between crankcase/cylinder, not that the air going in and out of the crankcase is the problem. Both engines types suffer from pumping losses on the exhaust side to a certain extent.
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In an average car, a diesel results in about twice the mileage during the EPA combined cycle. As the percentage of load increases, i.e. we have smaller engines in bigger vehicles, or smaller engines doing more work, the advantage drops off. So with something like a small pickup that's always carrying a half ton, there's only a couple mpg difference. But for something that's generally not using all the engine has to offer, it's significant.
2005 Volkswagen Jetta EPA Fuel Economy Fuel Type Diesel MPG (city) 38 MPG (highway) 46 MPG (combined) 41 Fuel Type Gasoline MPG (city) 24 MPG (highway) 31 MPG (combined) 27 The EPA takes into account the extra ~16-18% energy per gallon diesel fuel has, so if driven according to the EPA schedule, the diesel will get something like 48mpg combined real world, versus 27 for the gas version. About a 78% increase in mileage compared to the 47% of a hybrid. Not to say gas hybrids aren't a good idea as well, in the same car a hybrid system makes for a big increase. 2006 Honda Civic EPA Fuel Economy Non-Hybrid MPG (city) 30 MPG (highway) 40 MPG (combined) 34 Hybrid MPG (city) 49 MPG (highway) 51 MPG (combined) 50 A hybrid diesel would be better than anything, but the extra weight of the hybrid system won't see the gains like in a gasser, and idle shut-off/free-wheeling transmission help out as much, so it's more economical to leave it out. At least until we start seeing 20-40 mile plug-ins. |
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