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#11
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Elmo P. Shagnasty wrote:
> In article >, > wrote: > > >>I get 46 overall, with 50+ at 70mph on the freeway. >>2003 CVT. 50,000 miles. > > > Wow. > > A buddy of mine, on a complete lark, went and bought a used Beetle > diesel. 47K miles on it. > > His first full tank, in town, with the AC blowing hard, was 47mpg. > > I have yet to hear what his first highway drive did. you know, this whole economy thing has really gotten me interested. especially as you mention the diesel thing. on the one hand, diesel is more thermodynamically efficient, so it's going to give better economy anyway, but diesel fuel also doesn't offer the same degree of latitude for, er, "variance" that gasoline does because it can become smoky, hard to start, or worse, ruin injection equipment. since that recent octane thread we had, i've been doing a little more reading around on the subject of calorific content for gasoline, and there really is a /huge/ reluctance by anyone [in the california market at least] to quote figures for the energy content of their fuel. i find this interesting because all other consumer goods are subject to performance standards, not least of which is natural gas which is sold by the therm, not the cubic foot. even gasoline is subject to rigorous weights & measures inspection with state inspectors certifying pump calibration at regular intervals. but, think about it, if you're selling energy not by actual calories [therms in the case of natural gas] but by volume [gallons], the relevance of the volume measurement is somewhat questionable if the energy content is variable. so, what do we have here? http://api-ec.api.org/about/index.cf...02001000000000 and to repeat the most interesting paragraph in the whole page: "Conventional gasolines also can contain oxygenates. They are added to help meet octane number specifications and/or to extend the product volume." extending product volume??? if using ethanol "volume extender", it has about half the calorific content of gasoline meaning you need to burn /more/ gas gallons to travel the same journey. hopefully, the cost impact of this is obvious, but in case it's not, consider this. imagine you're flying to tokyo from san francisco, [about 1000 miles] against the jet-stream all the way. the pilot & engineer carefully calculate their fuel requirement for the journey based on their payload, known winds, distance, etc. imagine now that they were buying fuel in gallons and that unknown to them, the energy content of their fuel had been reduced by 10%. that could leave them stranded in the ocean by nearly 100 miles. so, while i don't know this for fact, you have to assume that either there is a base minimum energy content for aviation fuel, /or/ that the energy content is known at the time fuel calcs are done. if there is a base energy content for aviation fuel, why not for cars? it affects the amount of money i spend at the pump each week. if the energy content is known, why not for cars? it affects the amount of money i spend at the pump each week!!! i'm now /definitely/ interested in this whole oxygenation thing. fwiu, oxygenates are irrelevant for modern closed loop injection systems, so could it be that the emphasis on oxygenates are actually the result of the opportunity to use "volume extenders"??? > > I'd think a Toyota Corolla could come close enough to that 46 overall > number, and that without having any black magic software/hardware that > no one but the dealer can fix. > |
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#12
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In article >, jim beam > wrote:
>since that recent octane thread we had, i've been doing a little more >reading around on the subject of calorific content for gasoline, and >there really is a /huge/ reluctance by anyone [in the california market >at least] to quote figures for the energy content of their fuel. It is true they vary. Diesel is denser than gasoline, and thus has about 12-13% higher energy content (and about 12-14% more GHG production) per gallon. Thus that part of the MPG benefit is not about efficiency, just energy density. Ethanol has about 2/3 the volumetric energy content of gasoline. If one uses as much as 10% ethanol, I calculate roughly a 4% decrease in energy content overall. That's just an approximation. I'm not sure of the exact value. And I suppose most reformulated or oxygenated gasoline uses less, so less deviation from "pure" gasoline (which varies in itself). So yeah, there are energy density differences, but not huge. |
#13
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muzz wrote:
> On 21 Jul 2005 10:06:57 -0700, "Jeff" > wrote: > > Good night! I've had my 2004 now for 18 months and am getting > 32 mpg. Dealer says that's about the expected mpg - excuse me? > I think I should get at least 40 if they advertise 48. Had the recall > computer update done last week, but they say not to expect any > better - a) what are your driving habits like? b) did you do any research on the hybrids before buying? |
#14
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jim beam wrote:
> you know, this whole economy thing has really gotten me interested. eh. kinda bores me. seeing all these people shelling out beaucoup bucks on a new toy trying to justify it by saying itll save a few cents on gas, and then getting all sentida when it doesnt work out as planned. wanna save money? buy any small honda or toyota. new or used. wanna be a little different? get some form of VW diesel, new or used. IIRC them advertising over 500 miles on a tank, but diesel might take a little effort to find. and then you have to deal with the VW quirks, like loose engine tolerances and oil burning. |
#15
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Elmo P. Shagnasty wrote:
> In article >, > jim beam > wrote: > > >>>A buddy of mine, on a complete lark, went and bought a used Beetle >>>diesel. 47K miles on it. >>> >>>His first full tank, in town, with the AC blowing hard, was 47mpg. >>> >>>I have yet to hear what his first highway drive did. >> >>you know, this whole economy thing has really gotten me interested. > > > That's the goal: get people thinking and educated. > > BTW, my buddy tells me that he gets 52+ mpg with that Beetle on all > highway miles. > > I'd *much* rather have a diesel than a hybrid, if mpg is the same and > the fuel is roughly the same cost. > im glad people are buying hybrids, but i think too many get their hopes up too high. hearing people complain that they arent getting 50mpg, but only 40 or whatever is as annoying as the guy at work bitching that it took $80 to fill his suburban. |
#16
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#17
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Elmo P. Shagnasty wrote:
> In article >, > jim beam > wrote: > > >>>A buddy of mine, on a complete lark, went and bought a used Beetle >>>diesel. 47K miles on it. >>> >>>His first full tank, in town, with the AC blowing hard, was 47mpg. >>> >>>I have yet to hear what his first highway drive did. >> >>you know, this whole economy thing has really gotten me interested. > > > That's the goal: get people thinking and educated. > > BTW, my buddy tells me that he gets 52+ mpg with that Beetle on all > highway miles. > > I'd *much* rather have a diesel than a hybrid, if mpg is the same and > the fuel is roughly the same cost. > i used to do a lot of maintenance work on diesels. in many respects, they're great, especially for towing. and interesting to drive too - a huge contrast to a honda where it's all about the revs. but i /hate/ diesel fuel. i hate it on my hands. i hate it on my clothes. i especially hate it if i get it on my shoes because it stinks & you can't usually throw them in the washing machine like practically everything else. i'd also regularly see cracked cylinder heads. maybe the newer direct injections are less problematic, but the older indirect injection engines would always crack around the pre-combustion chamber. there's massive thermal cycling & very high pressures in that location so it's /going/ to happen. depending on the vehicle, many would last well over 100k miles, but even so, cracked heads were pretty much inevitable and /very/ expensive to replace. old diesel indirects with cast iron heads often last much better, but they're not immune by any means and i can't imagine they're used much any more because of weight & emissions. |
#18
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"im glad people are buying hybrids, but i think too many get their
hopes up too high. hearing people complain that they arent getting 50mpg, but only 40 or whatever is as annoying as the guy at work bitching that it took $80 to fill his suburbanan." If Honda is advertising it at 47/48 mpg, I'd like to know if something can be tweaked to reach that mark. Should I just sit back and say "well, 40 isn't too bad"? Hell no. If I'm going to pay the extra few grand to get the Hybrid over the standard Civic, I want a return on my investment. And hearing someone complain about 40 mpg is not even in the same ballpark as listening to a suburban or better yet, a Hummer owner, complain about their gas bill. Apples and oranges. |
#19
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Elmo P. Shagnasty > wrote:
> In article >, > wrote: >> I get 46 overall, with 50+ at 70mph on the freeway. >> 2003 CVT. 50,000 miles. > A buddy of mine, on a complete lark, went and bought a used Beetle > diesel. 47K miles on it. > His first full tank, in town, with the AC blowing hard, was 47mpg. The VW golf TDI was on my short list. At first I didn't think I'd like it, remembering a VW Rabbit diesel rattling in my driveway in the 70's. The new TDI is pretty quiet. You can hear something rattling around, but it is a different pitch than what I remember and not obnoxious. The smell of diesel is still there, which varies greatly from time to time and vehicle to vehicle. There is also a drop in MPG between 5 speed and automatic. The EPA rating is 42 hwy with auto. The EPA rating for highway 5 speed is 47, and the personal reports on fueleconomy.gov indicate that the A/C might not have been the only thing blowing hard for your friend. The city ratings for stick and auto are 38 and 35. The Golf suffers more in the city. The difference is 42/34, higher stick, lower automatic. I hadn't looked at the Beetle. The TDI diesel was redesigned in 2004 for higher mileage than what was available when I was shopping. --- Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5 |
#20
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In article . com>, "Jeff" > wrote:
>If Honda is advertising it at 47/48 mpg, I'd like to know if something >can be tweaked to reach that mark. Should I just sit back and say >"well, 40 isn't too bad"? Hell no. If I'm going to pay the extra few >grand to get the Hybrid over the standard Civic, I want a return on my >investment. There is no guarantee that you will get the 47/48. Those numbers are based on standardized tests that won't necessarily be reflective of how you drive, nor where you drive. Having said that, it does seem that hybrids miss their EPA sticker MPG by a higher pct than do other vehicles. And I can certainly see why the buyer of such a car might be miffed. However, there are reasons why a hybrid might miss by mo the hybrid power management strategy is more highly dependent on the drive schedule it is tweaked for than the normal transmission/vehicle strategy in a conventional vehicle. A high mpg vehicle will be impacted more by turning on A/C, or opening windows, or any similar since it consumed so little fuel otherwise. Last, consider how much extra fuel is consumed if you get "only" 40 mpg vs 48. Over 12,000 mi/yr, it would consume 50 gallons more. A gallon/week. That's equivalent to a 24 MPG rated vehicle only delivering 22. I think we would benefit from the EPA's certification cycle more closely resembing "typical" (whatever that is) driving. So that hybrids would more likely be tweaked for, and approach, real world MPG. So I hear your lament. But I also can see why some would not be terribly concerned about the differences between 48 (rated) and 40 (real) mpg. |
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