VW Jetta TDI

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Comments

  • ruking1ruking1 Member Posts: 19,826
    It is not normal at all. The first order of business is to eliminate all the likely suspects. So a trouble shooting session with your local guru on a VAG.com would probably be in order. It could be as simple as adjusting your IQ.

    The BEW TB/WP interval (replace) is clearly @ 100,000 miles link title
  • csmcsm Member Posts: 37
    Some time ago my fuel door quite locking and just the other day I went to close the trunk and now it won't lock.

    I have tried over and over to shut it... operating the switch several times and trying again and again to latch it... with no avail... it just quite latching.

    Any solutions as to why these two latches have stopped operating?

    Thanks for your input.
  • morey000morey000 Member Posts: 384
    OK-
    Let's pretend for a moment that I'm clueless (not hard to do)

    What is so special or unique about the DSG auto tranny? How is it different than a 'regular' automatic transmission and what benefits does it offer. What disadvantages (if any)? complexity/cost/peformance?

    thanks in advance

    Strike that request. A bit of a search and I found this description:
    http://cars.about.com/od/thingsyouneedtoknow/a/ag_howDSGworks.htm#
  • inlarryinlarry Member Posts: 13
    Alrighty, next question is since the vehicle has 67xxx miles on it, it's clearly out of the normal warranty. Would this (likely?) fall under the emmissions warranty?
  • gagricegagrice Member Posts: 31,450
    My guess is you were using a lot of high sulfur content diesel before the ULSD mandate in 2006. That will clog up the emissions system and result in what you describe. My first guess is it should be covered under the emissions laws. However most states do not test diesel cars for emissions. So it may be an uphill battle. Another observation. Some of the early Prius with very expensive exotic emissions systems were destroyed by high sulfur gas sold in most of the USA. Toyota did not warranty according to posters here on Edmund's. The claim was cheap gas caused the problem.
  • siberiasiberia Member Posts: 520
    Hey folks, I'm driving a 2005 (previous body) TDI with about 67000 miles. I've noticed recently that my exhaust under slightly rough to hard excelleration ranges from somewhat "smokey" to "i'm driving a 1980 Peterbilt". How normal is this?

    Inlarry, are you sure it's as bad as you describe. I have the same car and if I drive around town for a few days I get a pretty good build-up that blows out the first few times I accelerate to highway speed. Then, it pretty much goes away unless I punch it to the point of downshift. How is your fuel economy? If you are blowing a lot of black smoke because something is wrong your fuel economy should be dropping. I'm getting around 44 mpg ave with an automatic and it will blow some pretty good smoke once in a while.
  • ruking1ruking1 Member Posts: 19,826
    Indeed even those "1980 Peterbilts" have to NOW run ULSD and as a result do not have NEAR the soot and smoke of LSD and above (ppm sulfur). The only exception I can currently think of are farm and construction equipment and even red dyed D2 is starting to be ULSD. Trucks from Mexico would be another exception as I understand ULSD is NOT required even to enter the USA. Now burning oil (various colors of smoke) can be an issue, but not likely.
  • sandman52sandman52 Member Posts: 36
    You don't mention what year your vehicle is, but I had a similar problem with the trunk latch on my 2005.5 new style Jetta about a year and a half ago.

    It turns out that it was a known friction problem with the latch/cable mechanism, where the latch wouldn't completely return to it's closed position after being opened. In my initial phone inquiry, I asked about the problem being a known one, and if so did they have the parts on hand? I was told that they hadn't heard of it before, and I would have to bring it to see what the problem was. When I brought it in for diagnosis/repair the first thing out of the service managers mouth was " if it's your latch mechanism, we won't be able to fix it today, because we have 50 of them on back order" which of course required a second 140 mile round trip for repair. I haven't had the problem with the fuel door latch, but it's quality always feels a little suspiciously "Mickey Mouse" when I use it. Even if your car is out of warranty, I would press them for a free fix on at least the trunk latch, since this is certainly not an isolated problem, and was clearly either a design, or production defect.
  • csmcsm Member Posts: 37
    Thanks Sandman;

    Sorry... it's an '03. Thanks for the input. I will contact them and see what gives.
  • relprelp Member Posts: 3
    """Aren't the ratings for this car around 29/40? If so why do you say the hwy rating is "way off" while you say the city rating is "pretty close" at 38mpg even though it is farther from the EPA estimate than your hwy mpg"""

    My mistake.. I meant 28 mpg. My city mpg fluctuates in the 28 to 31 mpg.
  • autoboy16autoboy16 Member Posts: 992
    DO NOT change at 100k! The plastic water pump impeller is prone to start leaking around 75k. So IMO, its best to get BOTH change AT 80k miles. TAKE TO A VW SHOP, NOT a STEALERSHIP!

    Also, DIYers, ecstuning.com carries both the METAL water pump and Timing Belt for roughly $260 for both.

    Shop will charge about $600 for both vs $1200 at the dealership.
  • ndmike88ndmike88 Member Posts: 155
    Just picked up an '09 TDI on Saturday. I was reading the maintenance booklet and I am confused. Does the oil need to be changed every 5,000 miles or at 5,000 than 10,000 then 20,000, 30,000...........????
    Thanks
  • ruking1ruking1 Member Posts: 19,826
    The 2009 has a first oil change recommendation @ 10,000 miles. .... Then 10,000 miles intervals there after. So the next interval should be @ 20,000 miles.

    "DO NOT change at 100k! The plastic water pump impeller is prone to start leaking around 75k. So IMO, its best to get BOTH change AT 80k miles. TAKE TO A VW SHOP, NOT a STEALERSHIP!

    Also, DIYers, ecstuning.com carries both the METAL water pump and Timing Belt for roughly $260 for both.

    Shop will charge about $600 for both vs $1200 at the dealership. "

    There are a number of procedures to take some of the guess work out of the equation, if you do not trust the 100,000 miles OEM recommendation. Two are to visually inspect the timing belt, and the water pump. While you are at it inspect the serpentine belt. Another is when you start to have coolant (G12) consumption issues. The most likely culprit is play in the impeller which will leak coolant at the weep hole.

    There are a LOT more parts to a TB/WP "kit", than the two pieces. They are potentially AS important as those two pieces. link title

    There is a third option and that is a TDI guru at a local GTG. It was @ the first price that you mentioned.

    The 2009 TDI Timing Belt and Water Pump oem recommendation is @ 120,000 miles.
  • bpeeblesbpeebles Member Posts: 4,085
    I agree, the best choice for DIY folks is to purchase one of the available TimingBelt "kits" which includes every nut,bolt, pully, gasket, thermostat, brass-waterpump that you will need.

    Here is a sampling of the available kits

    Here is another sampling of kits

    If you are not inclined to tear your engine apart yourself... you can find a VW guru who is willing to do the job.

    BTW: Do not forget to check/replace the crank and camshaft seals while the TB is being replaced.

    Anyone who does the "cheep" option and replaces just the TB is asking for trouble.... the rest of the moving parts WILL NOT go another 100,000 miles and when they break... your engine may be destryed.
  • lostlost Member Posts: 64
    Does the 2009 TDI have a timing belt or a timing chain?
  • fho2008fho2008 Member Posts: 393
    Sounds like its a belt.
  • tdifuntdifun Member Posts: 10
    Hello, just picked up a new TDI jetta with DSG. It seems slow when taking off, is this normal. Its like a lag between the gas peddle and when it takes off. Does the trans need to just be driven a bit more?

    I sort of wish you could hear the diesel a little more.. heeehee..

    18 miles and counting.
  • dieselfitter1dieselfitter1 Member Posts: 42
    GOOD FOR YOU! I have a 09 TDI Wagon.
    The DSG electronics is learning when to shift. Use sport mode to break in engine properly.
  • ruking1ruking1 Member Posts: 19,826
    It really depends what you compare it against.

    Like that marbles in a can sound eh? ;) This thing has only got a 16: ?? to one compression ratio!! You really need 25 to one for that GOOD marbles in the can sound!!

    Indeed two absolute best things you can do are:

    1 know and understand the parameters of the turbo diesel AND most importantly OPERATE it within those parameters

    2. emphasize proper break in for a min of 10,000 miles. Indeed full break in, aka full compression does not happen untill 30,000 to 60,000 miles.

    All the best !
  • oceanrunneroceanrunner Member Posts: 1
    Are you guys just waking up to this? Almost all auto makers in Europe offer diesel models, (Ford, GM, Chrysler, Honda, Hissan, Toyota, VW, Mercedes, Hyundai, Kia, etc.) so someone is keeping diesels off the US roads. I suspect that the Oil companies are behind this, but the State owned Auto companies are equally to blame, as is the EPA.
  • longo2longo2 Member Posts: 347
    Yes, that's a mystery that no one wants to solve.

    Case in point, when the Honda 2.2 ltr diesel engines were inspected, the EPA failed the one with the a/t and passed the one with the standard, causing Honda to drop the whole diesel idea for North America.
    The Honda test vehicles were getting 56 mpg on the highway in an Accord sized car .

    Dirty Diesel trucks, yes, diesel heavy ecquipment, busses and giant, soot spewing ocean going ships burning sludge, fine, but don't let a little car engine put out so much as a speck of polution.

    The VW 2 ltr diesels have now passed every roadblock put in their way by the EPA and are selling like hotcakes...someone must be PO'ed!
  • dice4dice4 Member Posts: 9
    Exactly! I have a full sized SUV 5/7 passenger Rexton made in Korea with a Mercedes engine and transmission, 2 speed 4WD that gets over 30 mpg purchased in Panama. Wish I could take it back to the states. Will purchase TDI,upon my return. Haven bought an american made auto in 35 years for that reasion.
  • jim314jim314 Member Posts: 491
    In the past the cost of petroleum motor fuels was so low in the US compared to Europe that the lower cost of a gasoline spark ignition engine gave it a huge advantage over the diesel engine. Americans usually wanted more power than a diesel could deliver for a given weight of engine. Also maybe there was just such a stgrong US tradition in the use of gas engines in cars.

    Then there is the fact that we have been more environmentally conscious than the Europeans. (For example, we were the world leader in discontinuing leaded gasoline, which I think everyone now would say was the right path to take.) In order achieve the same exhaust standards as gasoline engines for fine particulate emissions and NOx special systems had to be invented for mass production which have only been available for the past few years. These systems reduce mpg and are a considerable expense.

    It seems to me that gelling of diesel fuel is a problem in the US. People here can drive from a relatively warm area to a below zero in one day.
  • jkinzeljkinzel Member Posts: 735
    Are you guys just waking up to this?

    The fact that most passenger cars offered in the US have a diesel counterpart in almost every country in the world is well known fact, at least to the people on this and the diesel threads. And the fact that all the US and Asian auto makers refuse to jump into the diesel passenger car market has been a mystery to everyone.
  • gagricegagrice Member Posts: 31,450
    It seems to me that gelling of diesel fuel is a problem in the US. People here can drive from a relatively warm area to a below zero in one day.

    Trucks rumble across this nation daily from desert to sub zero temps. It is a non issue with D2. It is usually mixed with D1 in very cold areas to avoid gelling. Jets use D1 (jetA) at 40 below zero on a daily basis. Biodiesel is a bit more prone to gelling in colder climates.

    It was mainly our adoption of ULSD that cleaned up the diesel exhaust. Like leaded gas we have known that was an issue for decades and the EPA ignored the problem. So we smelled the nasty fumes caused by sulfur in diesel from all the trucks, buses, ships, trains until they finally got around to mandating clean diesel. The amount of NoX is very small that requires the extra equipment to clean. It is just a stumbling block put in by the EPA and CARB that are controlled by special interest money.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    I don't think it's really a mystery, although no doubt frustrating to diesel fans.

    1. Americans don't like diesel cars, and never have. The absolute best the diesels ever did, during the huge gas panics of the 70s (gas wasn't just expensive, it wasn't even available) was a diesel car market share of about 6%.

    2. Diesel fuel prices in the USA totally negate the big advantage most Europeans enjoy in fuel savings.

    So really there doesn't seem to be enough of the market share pie for most automakers to endure the expense of engineering diesel cars for the U.S. market IMO and its regulations.

    One could argue that attitudes change, and that Americans will come to like diesel cars if they had some to buy---but no automaker apparently wants to follow VW and Benz briskly into the market---probably it's a wait and see kind of thing.

    But really, diesel fuel prices kill the whole enterprise. No conspiracy necessary.

    I think the TDI is a great little car. I'd certainly consider buying one if diesel prices encouraged it.

    Visiting Host
  • ruking1ruking1 Member Posts: 19,826
    1. The snap shot today puts the diesel market @ 2% (5.108 M vehicles). As for the Americans not liking diesel, it is more like the behind the scenes actions/forces that shapes the "playing field. " Item #2 may or may NOT be self explanatory...

    2. Cost per mile driven usually gives the advantage to diesel. The price per gal differentials (RUG to PUG, D2)( given the logic presented) really do not explain the MUCH higher percentage of vehicles that use PUG rather than D2, as PUG is usually both higher than RUG AND D2. This really hides (in plain sight IMO) the inherent diesel advantage 20-40% RANGE over RUG to PUG despite the market flucuation of the diesel pricing.

    Indeed if you follow the per gal pricing logic (converted to per mile driven) , would you then therefore conclude: Americans LIKE to pay MORE per mile driven ..... than less (D2)!!??

    Specifically (currently) 107% and 122% per mile driven MORE than D2 !!!!

    Here is a for example 2003 VW:

    (one can run a range of prices and scenarios)

    2.0 RUG 2.91/25 mpg= .1164 cents
    1.8T PUG 3.11/25 mpg= .1244 cents
    1.9T D2 2.75/49 mpg= .0561 cents
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Yes but there are gasoline cars that offer far better MPG than VW's 25. And the diesel car costs quite a bit more to buy in the first place.

    The economics for diesel cars just don't "work" unless you spread out the costs over a much longer period that most Americans hold onto cars for.

    For Americans to embrace something "new" it has to be a no-brainer, like it was with the Prius. It takes about 2 minutes to figure out that you can get a roomy 5-door hatchback to deliver 45 mpg reliably on regular gas. No further calculations necessary.

    Gasoline cars are so efficient that they may even sink the hybrid versions of their own brand!
  • ruking1ruking1 Member Posts: 19,826
    No doubt, but that misses the essential factor- like models. @ the time the diesel premium was $246 over the 1.8T.

    For another example I have a Civic gasser. A LARGE percentage don't mind paying the 1,100 premium for an automatic that gets LESS mpg over the life of the machine, for discussion purposes per 100,000 miles.

    As a reality check, I get (an already great) 38-42 mpg in a point a to point b commute, the Jetta TDI gets 48-52 mpg. For a lot of other reasons (other than mpg) it is an almost TOTAL apples to oranges comparison.

    Honda (Civic) as you know offers TDI 's world wide (WW). I can easily get 56 mpg on a turbo diesel Civic. It would be a wash if I paid the diesel premium and got a manual transmission. Indeed this is true for OTHER Civic offerings and they cost WAY more aka hybrid, CNG.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    The TDI vs. 2.0T in the Jetta has pretty much evened up on MSRP, which is GOOD, but the TDI mpg is now listed at 34 mpg averaged out. And that's exactly what the Edmunds longterm TDI is getting (so far). I don't think 52 mpg is going to be a real world number for most people upon which to base their calculations concerning "should I or shouldn't I?" We are not all hypermilers.

    I agree with you though, the more diesels on the American market, the better for VW and for all diesel car makers.

    The TDI is popular, has very good resale value and seems more durable than the run of the mill VW.
  • ruking1ruking1 Member Posts: 19,826
    Indeed that is too true. However if you STRUCTURALLY get 20-40% OVER (one individual variation)is that BETTER or worse?????

    The real question/s remains unchanged.

    By default and defacto it is however ANSWERED ; by the 98 % passenger vehicle fleet that is gasoline (RUG to PUG)

    To finish on the Civic there are whole standard deviation of Civic (others oem's also) that are mildly to wildly disappointed about these "economy" cars.

    There is another undeniable fact. It is the ratios of usable RUG to PUG to D2 in a refined barrel of oil. While undoubtably it can be twiked, the fact is you can not get a 100% RUG to PUG from a barrel. That being true a population of 23% diesel will (instantly) drop the over all demand of oil (domestic and foreign). This would be even before the 20-40% diesel advantage. So despite the hot air on the subject, it would seem it is not that important as professed.
  • ruking1ruking1 Member Posts: 19,826
    ..."To finish on the Civic there are whole standard deviation of Civic (others oem's also) that are mildly to wildly disappointed about these "economy" cars."...

    Change to:

    To finish on the Honda Civic, there are whole standard deviations of Honda Civic owners ( owners of other oem's also) that are mildly to wildly disaapointed about these "economy" cars- mpg.
  • Mr_ShiftrightMr_Shiftright Member Posts: 64,481
    Well I dunno...the Honda Civic is one of the best selling cars in America. Detroit and VW should build such disappointing cars :P
  • jogousajogousa Member Posts: 402
    Well, the price issue is no longer applicable. In my neck of the wood (Pensacola, FL) price for diesel is lower than regular gasoline. With cetane in the 60's it's a pretty good deal!
  • jogousajogousa Member Posts: 402
    Keep on adding those miles. There is certain "lag" if you run A/C and that may be the reason for it. As A/C compressor kicks on and off with 1,9 liter engine you will feel certain "lag" - but that is not turbo related.
  • jogousajogousa Member Posts: 402
    Not to mention Subaru - Forester diesel is running in Europe second year already. I was waiting for it here but did not meet Calif. EPA. So I bought 2009 Jetta Tdi SportWagon instead. Subaru tried to purchase Daimler Benz (BlueTek) technology (urea injection into exhaust) and VW/Audi (recycling and burning exhaust solids) but the price for royalties were too high (according to Subaru insiders) so Fuji Heavy Industries (owners of Subaru - formerly Nakajima Aircraft Co that was shut down by US allies during WW2) is developing their own version that will be all US States legal. Flat 4 boxer Subaru Diesel (virtually no vibration thanks to flat cylinders running in opposite directions) will be the ultimate car, in my opinion, to own on these shores.
  • ed_granted_grant Member Posts: 10
    The US consumer is the one at fault. Gas prices haved come down and buyer are back eating SUVs. We need a $3.00 per gallon tax that would fund certification of any manufacturer wlling to bring a deisel into the US. Also expansion of the tax credit for buyers of green cars, including deisels. In addition dealers could not add additional markups on any green car.
  • ruking1ruking1 Member Posts: 19,826
    ..."We need a $3.00 per gallon tax that would fund certification of any manufacturer wlling to bring a deisel into the US."...

    Don't say that too loud !! Or too much !! Actually I should not say RUG to PUG is 107 to 122% more expensive than D2. (msg #2943) It is truly nice to run it cheaply at this ... place and time.
  • bpeeblesbpeebles Member Posts: 4,085
    You must be thinking of another type of car.

    VW uses a "variable volume" A/C compresser... the only ON/OFF is when you turn on/off the A/C. Once the A/C is "on" and the clutch enguaged, the compressor varies the volume of freon it compresses based on the demand... but the compressor always spins because the A/C clutch does not cycle like other designs.

    I still get up to 56MPG with 3 people in the car, trunk full of luggage, 85+ degrees outside and the A/C on full. (I have a spreadsheet showing every drop of fuel I have pumped into my TDI.)

    Anyone who thinks a modern diesel does not make economic sense has not looked at the complete picture with an open mind. Better MPG, lower-cost maintenance and you are not driving around in a tincan-feeling hybrid. (Which, by the way, runs on the engine all the time while on the freeway...so the batterys are just dead-weight.)
  • karthur1karthur1 Member Posts: 7
    Looking to purchase and trying to determine between Bill Jacobs (Naperville) and Pugi (Downers Grove)... any experiences good/bad?

    Thanks!
  • karthur1karthur1 Member Posts: 7
    I am looking to purchase a Jetta 2009 TDI and am trying to figure out what I should pay and which warranty I should buy for it. I will put nearly 30,000 miles per year on it so the standard warranty will blow out in a matter of a 1.25 years. I need this car to at least last me 100,000 to 160,000 miles (to cover the 5 year financing).

    Best warranty and cost/price from VW? Can't find much info on the official VW website.

    Thanks,

    Kris Arthur
  • eliaselias Member Posts: 2,209
    a civic diesel would get HUGE mpg: 140% or 150% of gasser civic's mpg.
    (comparing VW TDI with smaller/lighter gasser cars that get 37 mpg is not an apples-to-apples comparison.)
    Although I prefer VWs today, I civics and have owned 3, for ~200k miles total.
    (90 base/hatch, 92 EX, 93 LX) . the civics' highway mpg dropped from >40 to <30 when california RFG1 was introduced. :(
    Yesterday I was conversing with an ancient pal who once had a CVCC engine disassembled on his kitchen table. The pistons were so tiny - they looked like they were from a RC aircraft.
    [edit: maybe i should say "fit" instead of "civic" in this post! today's civics are as
    large as accords were back when i owned civics - and the jetta is probably bigger than passat was back then! ;) ]
  • patpat Member Posts: 10,421
    Hi, welcome!

    Try looking up dealers in our Dealer Ratings & Reviews feature. Also you can ask others who are hanging out in our Volkswagen Jetta Prices Paid & Buying Experience discussion as well as the VW TDI Models Prices Paid & Buying Experience topic.

    Good luck - let us know how it goes.
  • jim314jim314 Member Posts: 491
    The mpg advantage of diesel over gasoline cars is misleading (falsely high) because diesel fuel is 18% denser than gasoline. Comparisons should really be done by weight of fuel. So divide the mpg of a diesel by 1.18 to compare to gasser, or multiply the mpg of a gasser by 1.18 to compare to a diesel.

    "The density of petroleum diesel is about 0.85 kg/l (7.09 lbs/gallon(us)), about 18% more than petrol (gasoline), which has a density of about 0.72 kg/l (6.01 lbs/gallon(us)). When burnt, diesel typically releases about 38.6 MJ/l (138,700 BTU per US gallon), whereas gasoline releases 34.9 MJ/l (125,000 BTU per US gallon), 10% less[5] by energy density, but 45.41 MJ/kg and 48.47 MJ/kg, 6.7% more by specific energy. Diesel is generally simpler to refine from petroleum than gasoline. The price of diesel traditionally rises during colder months as demand for heating oil rises, which is refined in much the same way. Due to recent changes in fuel quality regulations, additional refining is required to remove sulfur which contributes to a sometimes higher cost. In many parts of the United States and throughout the UK and Australia[6] diesel may be higher priced than petrol.[7] Reasons for higher priced diesel include the shutdown of some refineries in the Gulf of Mexico, diversion of mass refining capacity to gasoline production, and a recent transfer to ultra-low sulfur diesel (ULSD), which causes infrastructural complications.[8]
    http://en.wikipedia.org/wiki/Diesel_fuel"

    The true measure of efficiency of a piston internal combustion engine is the so called brake specific fuel consumption (BSFC) which is weight of fuel consumed per unit time per unit power output. In English units this is lb / hp-h and in metric units this is g / kWh.

    An advantage of gasoline is that it is relatively higher in hydrogen than diesel fuel. Natural gas (methane CH4) is higher in hydrogen than gasoline. The lower the moleular weight of a saturated hydrocarbon the higher is the amount of hydrogen relative to carbon. The molecular formula of a saturated hydrocarbon is CnH(2n+2). So the ratio of number of H to number of C in a saturated hydrocarbon is 2 + 2/n. So the ratio is 4 H per C in methane n = 1, about 2.25 for gasoline n=8, and about 2.14 for diesel fuel n = 14.

    After all these effects are taken into account a modern TDI diesel is currently still significantly more efficient (lower BSFC) than a sequential multiport injected gasoline engine of the same power output, and diesel fuel is much less of a fire hazzard than gasoline in case of a spill. But it remains a question as to whether the efficiency advantage of a diesel is enough to pay for the significantly higher cost of the diesel engine, and potentially higher maintenance costs over the life of the engine, e.g. glow plugs, high pressure fuel injection system.

    When the next generation of gasoline engines comes out (turbocharged direct inject gasoline still spark ignition) the differences will no doubt be narrowed, but then the cost of the gasoline engines will rise relative to the diesel engines.
  • gagricegagrice Member Posts: 31,450
    The one fact that remains. A diesel engine generates higher torque at lower RPMs than a comparable gas engine. While this is not a big plus if you like racing from stop light to stop light, it is a huge bonus out on the road. Not having to downshift on long hills and hear a screaming gas 4 banger is enough incentive for me to pay the difference. I cannot imagine the engineers overcoming this deficiency in gas engines.
  • ruking1ruking1 Member Posts: 19,826
    ..."a civic diesel would get HUGE mpg: 140% or 150% of gasser civic's mpg."...

    Indeed that is the utility of comparing apples to apples (like-models) . A Honda Civic diesel would overnight turn the already great economy car into a serious economy leader/king/queen for many MORE years to come. I think Ford/GM/Chyrsler would take the WC Fields line: go away boy, you are bothering me.

    Most folks understand the weight factor effects a (further) loss on mph. They might not know the rule of thumb (plus+/minus - : 1-2 mph per 100#'s)

    For example the weight difference between a 03 VW Jetta TDI and a 04 Honda Civic is 436 #'s (2950#'s 2514#'s) So a Civic getting 38-42 mpg (using the rule of thumb ) would now be 33.64 to 37.64 mpg vs a TDI of 48-52 mpg. This of course works vice versa also. (what mpg would the TDI get being -436 #'s lighter)

    Need another graphic? What do you think would be the difference in mpg would be with one person and 3 extra (normal weight) folks or 2 college football types (218#'s each)?
  • eliaselias Member Posts: 2,209
    jim-pi*100 , thanks for your detailed and thought-provoking data & analysis.
    diesel is less expensive than gasoline *per gallon* in most of USA currently, and mpg is indeed a crucial factor for bottom-line for drivers.
    I think a metric like "miles per pound of fuel" is more important for rocketry & NASA, and less important for passenger vehicles.
    I don't anticipate fuel being sold per unit weight or with prices normalized to take density into account - and until/unless fuel is priced like that, I conclude that your initial point is simply not correct: the one about diesel advantage being falsely-high/misleading. There's no falsity here.
    The cost to own/operate "is what it is" no matter if we use non-standard units to do the comparison.
    (Shall we compare using the number of drachmas per joule, or cubits per gallon?) ;)
    Buyers can always do the math given current fuel *per gallon* prices, and compare "true cost to own" in order to determine if the extra $200 or $1000 or $5000 cost for the diesel-engine is a likely "slamdunk" win for their situation.
    One possible optimizing strategy is to own two lower-cost vehicles instead of one big-$ vehicle. one gas, one diesel, driving each according to prices/conditions/needs and to minimize the price per cubit of driving.
  • ndmike88ndmike88 Member Posts: 155
    Bought my TDI almost 2 weeks ago. Dealer filled up the tank and computer shows I can still run another 200 miles. (for a grand total of almost 435 mles). My question is (and I'm sorry if this has been asked before) are there any differences between Shell, Amoco/BP, Exxon/Mobil .........? Is one better than the rest? Anything I should watch out for?
    Thanks
  • jkinzeljkinzel Member Posts: 735
    While your information is interesting, informative and appreciated, weight is not much of an issue for cars, trucks and boats.

    Regardless of weight the most important issue is that you can about 40% farther on a gallon of diesel as compared to a gallon of gasoline.
  • jim314jim314 Member Posts: 491
    Petroleum auto fuels are priced on volume measurement, but this is only a surrogate for mass. From a chemical and engineering perspective mass is the relevant measure of amount of fuel. For example modern cars have a mass air flow sensor, not a volume air flow sensor. Volume measurement is just a convenient way to measure the amount of incompressible liquid fuel.

    If all you want is to calculate the cost of driving a certain distance today, then, of course, all you need is the fuel volume consumed per unit distance and the price per unit volume. But if you want to ponder the relative merits of gasoline and diesel engines in the larger scheme of the environment and the economy, then a scientific approach is needed.

    The environmental regulations in Europe and in the US used for setting taxation or regulation of carbon emissions recognize that diesel fuel contains as much as 15% more carbon per unit volume than gasoline. The calculations of carbon dioxide release per unit distance travelled (g/mi, g/km) are to multiply the mpg by one factor for gasoline and a higher one for diesel.

    A scientific approach is also more likely to lead to a correct understanding of what the future prices of these fuels will be. From a scientific point of view diesel fuel is currently underpriced compared to gasoline and we must expect this would change if market forces would set the prices.

    Why wouldn't diesel fuel and gasoline be priced equally per unit mass or per unit energy content? At retail you buy meat, bread, beans and tomatoes by weight, right?

    Demand and environmental cleanup charges by the government (not cost of production) are what sets prices in a market economy with proper government regulation of the common envoronment. Already the introduction of ULSD has increased the price of diesel, and for that reason some people who demand that they be supplied as much fuel as they want at a low price were outraged at the insistence on forced introduction of this less polluting diesel.
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