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Fuel Economy and Oil Dependency

jimvetajimveta Posts: 96
How much power are you willing to give up for that last bit of fuel economy?

I get the impression that while there's a lot of attention on mileage in absolute terms and ensuing discussion on the cost of the more fuel effecient cars, there seems to be very little discussion if any, about fuel mileage in relation to power.

- production cars
- aftermarket cars and parts
- power band
(remember, unit-wise: [email protected] = torque x rpm)
- highway vs city
- cruising vs WOT
- gearing


  • buckwheatbuckwheat Posts: 396

    Getting closer to real world usage..
  • larsblarsb Posts: 8,204
    'Bout dang time they change the test !! People have been crowing about this for about a decade now at least !!! :shades:
  • sls002sls002 Posts: 2,788
    The EPA should conduct real test of fuel consumption instead of making it a part of the emmissions tests. A useful result would be to have a steady state fuel consumption at say 45 MPH, 60 MPH and 75 MPH so that one could see how well a vehicle would do on real world highways. Stop and go driving is a real mess. A cold engine will burn more fuel than a warm engine, so a 2 mile drive to work will result in a much worse comsumption rate than a 10 mile drive to work.
  • nippononlynippononly SF Bay AreaPosts: 12,726
    that the ratings will drop around 20%. They are going to start using the A/C during the test, and will also drive them real highway speeds (probably 65, I would guess).

    It will be a good thing. Right now they are kind of pie in the sky for many folks (although I personally always achieve mileage somewhere in between the two ratings).

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • scott1256scott1256 Posts: 531
    From Autoextremist today: mileage estimated to drop 5-20% on most cars.

    Hybrids will fall much more: 20-30%. This will be a hit for the hybrid market but may be more realistic.

    Page down a litte to the paragraph about mileage.
  • carlisimocarlisimo Posts: 1,280
    "and will also drive them real highway speeds (probably 65, I would guess)."


    As for hybrids, the new numbers may reduce showroom traffic, but they'll also reduce complaints by owners. Dealers have complained that they're legally not allowed to give realistic mileage numbers because you have to display the EPA figures.

    There could also be an effect on tall-geared engines like the Corvette (is "tall" correct?), which will suffer a greater change (proportionately) in revs at the more realistic highway speeds.
  • explorerx4explorerx4 Central CTPosts: 13,748
    i disagree about the corvette. real world highway mileage is very good. the engine will work better at 65 mph than the 55 or whatever the epa test uses. the corvette trick (1 to 4 shift) is to help the city mileage rating. to be honest, i don't know if it still uses that.
    2017 Ford Fusion SE 2017 Ford F-150 Limited
  • carlisimocarlisimo Posts: 1,280
    I think the EPA uses a 60mph maximum, with an average speed in the 40s (!). That means a lot of economy cars are forced to shift into a lower gear for some of the test, which puts them at a disadvantage compared to big engined cars (if I'm right about the current test). That was my line of reasoning, but real world info matters more. But if Corvette owners are getting their rated mileage, they really need to find some funner roads...
  • starrow68starrow68 Posts: 1,142
    Some cars, like the Corvette, have been tailored to the test to get a great result (no gas guzzler tax at 400hp or even 505hp), and that has resulted in some drivers getting very good real world results. However, the variation in milage for Corvette drivers is very wide since some don't like to get into 6th except for very high speeds while I'll use it on any flat road over about 40mph. Others like to listen to the exhaust note and stay in 4th and don't even get to 5th much. Don't have any experience in the older 4 speed autos. The new 6sp auto should be good news for mileage. At about 45mph on a flat road my instant mileage readout is at about 35mpg in 6th gear. Of course there are places you have to stop and idle in the real world, hence I average in the low 20's, while the wife who drives much more conservatively on take off than I do, averages in the upper teens, go figure.
  • robertsmxrobertsmx Posts: 5,525
    Does it follow suit, or sticks to its current standard?
  • sls002sls002 Posts: 2,788
    On long highway trips with my Seville I can average around 29 MPG by taking it easy. This is well over the highway rating. For local driving I average more than the city rating but less than the highway rating. Everyday driving is not something that the EPA tests can predict for anyone unless they happen to drive exactly like the test.
  • nippononlynippononly SF Bay AreaPosts: 12,726
    Doesn't the EPA max out at like 52 mph on the highway test? I think the most significant thing is probably that they will use the A/C during the test now.

    The place where cars like the Corvette will suffer is the city test, not the highway test. They are going to shorten the cycling from cold for that portion, I believe. So instead of 1 10-mile drive with 40-some stops (or whatever the exact test is - I know it is something like that), they will do something more like 1 5-mile drive with 20 stops and 2 2.5-mile drives with 10 stops. With the engine getting cold in between.

    robertsmx: CAFE stays the same. BUA-HA-HA-HA! That is going to hit the domestics a lot harder than the rest, I think, but we will see. The hybrids obviously will drop a TON in rating - I wonder how that will affect sales. They will probably still do significantly better than gas-only counterparts.

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • rorrrorr Posts: 3,630
    "robertsmx: CAFE stays the same."

    Yeah, I was wondering the same thing. Regardless of who gets hit the hardest, it hardly seems 'fair' that the government CAFE standards establish certain MPG milestones for the manufacturers to hit.....and then the government changes the way MPG is measured midstream.

    I'm surprised Ford/GM/DC aren't all screaming bloody murder...
  • nippononlynippononly SF Bay AreaPosts: 12,726
    Ford and GM already pay penalites on this every year because their fleet average falls below the standard. So maybe it is no big deal for them?

    I think they should have the right to make their own test realistic. And it will certainly serve consumers better. With the gas prices spiking all over the place, it would be nice if you could make some reasonable calculation of what gas was going to cost you in a new vehicle before you committed to the purchase.

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • larsblarsb Posts: 8,204
    This change will reverberate through the auto and government arenas, because a LOT of legislation and rules are in effect based on MPG.

    *ALL* of that legislation and all the rules will have to be modified for this change, because car companies will not be penalized all of a sudden after the 2008 model year tests for MPG that the new test "cheats" them out of.
  • rorrrorr Posts: 3,630
    "I think they should have the right to make their own test realistic."

    I'm in absolute agreement; I've felt that the EPA test has needed some tweeking for years now to more accurately reflect real-word results. And the more accurate the info made available to the consumer, the better.

    All I'm saying (and which larsb also pointed out) is the fact that there are reams and reams of government legislation which is based on EPA mileage #'s and a sudden change in the way the EPA does their test will have many many ripple effects.

    If it can be shown that the new EPA tests result in a fairly consistent 20% reduction in MPG ratings, I would be in favor of a similar 20% reduction in the CAFE requirements.

    Look at it on the flip side: what if the EPA changed their test criteria and it resulted in the MPG ratings suddenly INCREASING on average by 20%? Would it be 'fair' for the manufacturer's to still operate under the old CAFE requirements even though their fleet magically received a 20% boost in economy? Or would it be fair for the CAFE requirements to be adjusted accordingly?
  • nippononlynippononly SF Bay AreaPosts: 12,726
    aren't the CAFE standards already fairly pathetic? Lower them 20% and you might as well just cancel them entirely.

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • rorrrorr Posts: 3,630
    "Lower them 20% and you might as well just cancel them entirely."

    You're missing the point. Whether or not the current CAFE standards are 'pathetic' or not isn't relevant. If you change the way something is measured, then any requirements BASED on that measurement should be adjusted accordingly.

    Hypothetically, if the EPA had been UNDERESTIMATING fuel economy (so that real-world numbers were higher than the ratings), they might change their methods resulting in 20% HIGHER EPA numbers. This would result in the manufacturer fleet mileage numbers suddenly going up by 20%. Would you or would you not favor an adjustment to the CAFE requirements under that scenario?

    You have to be consistent. If you would favor adjusting CAFE requirements UPWARDS to reflect a hypothetical increase in EPA numbers due to changed methodology, you must also understand the rational for adjusting the CAFE requirements down to reflect a decrease in the EPA numbers.
  • mirthmirth Posts: 1,212
    Actually, CAFE will still be based on the old EPA test, so nobody will be getting hit any harder than they were before.
  • rorrrorr Posts: 3,630
    Makes sense in the short term.

    I'd be interested to know (long-term) how this is supposed to work as new models are introduced. Will each model carry two sets of EPA ratings? (one figured the 'old way' for CAFE purposes and one figured the new way for the window stickers/consumer information).

    This could work AGAINST the reasons behind CAFE. As a manufacturer, why would I make an attempt to increase my REAL-WORLD mileage by 10% if it would require the vehicle to be certified under the new EPA guidelines resulting in an EPA number 10% less than the old number under the old guidelines? Heck, I'd just leave the thing alone for as long as the EPA let me use the old numbers for CAFE.

    Personally, I'm glad the EPA methodology is being revised. For too long, the EPA numbers have been unrealistic. The problem now though is that, while it would be 'fair' to adjust the CAFE requirements in line with the new tests, it would be political suicide for someone to actually propose this.

    Too many folks educated in government schools to understand the rationale behind adjusting the CAFE numbers.
  • mirthmirth Posts: 1,212
    ...scrap CAFE altogether. At this point, any manufacturer that let's their MPG numbers slide are going to take a hit in the market anyway.
  • rorrrorr Posts: 3,630

    Thanks for ending my week on a high note! :)
  • 210delray210delray Posts: 4,722
    ...between CAFE and the mileage ratings on the window stickers. Those of you who say the CAFE ratings use the "old" EPA method are correct, but since the 1985 model year, the posted numbers on the window stickers have been reduced by 10% for the city and 22% for the highway.

    Under the new proposed scheme, window stickers will have to reflect the new test results, but CAFE for manufacturers will still be figured the old way. Otherwise, they WOULD be screaming bloody murder, especially those who make the most gas guzzlers!
  • sls002sls002 Posts: 2,788
    The FWD Cadillac Seville was rated 18 city 27 highway for 2003. The unadjusted numbers were 19.5 city, 34.5 highway. My 2002 Seville actually gets 27 easily, and 29 if one takes it easy on long trips. For city driving or local driving, I average more than the 18 MPG or even the 19.5 MPG that the EPA got. However, 34.5 on a long highway trip would probably only be possible if one cruised at 50 MPH.

    In my opinion, rating the MPG at a steady cruising speed of say 50, 60 and 70 MPH or perhap 50, 65 and 80 MPH would really show buyers what sort of MPG they might expect on long trips at whatever sort of speed they like to cruise at. Also, showing the effect of speeding on MPG would be quite instructive.

    A cold start, short trip MPG is very sensitive to the length of the short trip. This is why everyone gets a different city MPG. I get quite good city mileage because I currently live 10 miles from anywhere worth going to, and most of that ten miles is highway. I also limit my speed while the engine is warming up to 50 MPH till the temp gauge is fully warm, which takes about 5 miles on winter days.
  • nippononlynippononly SF Bay AreaPosts: 12,726
    5 miles? It should warm up sooner than that, and then you could get better city mileage. Shouldn't it?

    They run the EPA test at 52 mph max for the highway portion, right? It's no wonder the current ratings are so hard to achieve for most folks.

    Automotive News had an article this week about how AAA did an owner survey and then did their own alternate test, and neither one got close to the EPA ratings.

    Prius gets a 56 mpg combined EPA rating, owners are reporting an average of 37, in the AAA test it got 44.

    Explorer got 16.8 in the AAA test, as well as in the owner's reports, but 18.3 from the EPA.

    Silverado got 17.8 from the EPA, but only 15 mpg among the owners, and 13.9 in AAA's test.

    I always manage to get close to the highway figure in around-town driving, and 10-20% above the highway figure on long highway drives. The key to city driving is smooth acceleration and letting off the gas if you see a stoplight ahead you know you are going to have to stop at anyway. Plus combining errands as much as you can. On the highway, the key is to keep speed as constant as possible, without a lot of accelerating to pass, and letting up on speed a little on long grades.

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • sls002sls002 Posts: 2,788
    My Seville does take about 5 miles to warm up when I am cruising about 50 MPH on the highway (say 6 to 7 minutes) when the outside temperature is about 10 degrees Farenheit. What I mean by warmed up is when the temperature gauge reaches the center (normal) position. The oil is still warming up at this point, and probably takes 10 miles to reach operating temperature.

    I am getting around 23 to 25 MPG in local driving. The computer says about 23 in winter driving, but my computer is goofy since the transmission was worked on. It randomly adds about a half gallon of fuel to the fuel used which then lowers the average MPG.
  • 210delray210delray Posts: 4,722
    As I recall, the current highway EPA test has a maximum speed of 60 mph, an average of 48 mph, and no full stops. The highway test is also run on a warm engine.
  • sls002sls002 Posts: 2,788
    I do not think that the EPA testing can predict what everyone will get in city driving. Everyone has a different route to and from work. The best the EPA can do is predict some average, but that is more or less where they are now. I think that a more useful set of information would be steadystate fuel consumption at 3 different highway speeds: 45 MPH, 60 MPH and 75 MPH. The cold start city test is also useful.
  • nippononlynippononly SF Bay AreaPosts: 12,726
    I mentioned this elsewhere, but this is the more appropriate place for it:

    Does anyone think this will cause a revolution in consumer buying patterns? Will they now totally shift away from more powerful cars as fuel economy ratings under 20 mpg become common?

    Will they go further and downsize their next purchase, as even class leading 4-cyl midsize sedans will probably only get a rating of around 25 mpg, and midsize SUVs and crossovers will also be under 20 mpg?

    Or will they not care, and go right ahead, because gas is cheap and easy in the good ol' U.S.?

    OR will the whole thing fizzle out, as the new EPA test proves to be little better than the old one, because it is too difficult to predict (as posters here have pointed out) what real-world driving will produce for FE?

    2014 Mini Cooper (stick shift of course), 2016 Camry hybrid, 2009 Outback Sport 5-spd (keeping the stick alive)

  • rorrrorr Posts: 3,630
    Personally, I don't think the new ratings will change overall buying habits a bit. Most folks I know have known for quite sometime that the EPA ratings were on the optimistic side and only used the ratings for comparison purposes (in other words, if Car 'A' was rated 3mpg better than Car 'B' under the old standards, it will probably STILL be rated as 3mpg better. The two ratings will simply be lower.) I think they will STILL just use the ratings for comparison purposes. Afterall, that is what the ratings are INTENDED for.

    Just out of curiousity, why try to predict what the real-world FE would be? If in the buying process you are comparing (for example) a Civic Sedan rated at 30/40 and a Corolla Sedan rated at 30/38, all I would care about was that in the City they should get about the same mileage and on the highway the Civic might get about 5% better mileage.

    It wouldn't change my buying decision one iota if the new ratings were 20% lower (24/32 for the Civic and 24/30 for the Corolla). I would STILL expect to get about the same mileage in the city and maybe 5% better on the highway in the Civic.

    Or are you saying that folks go into the decision buying process saying "I must buy something which is rated at 30/40" and so, because the ratings get revised, they will just naturally seek out an even more fuel efficient car to achieve a predetermined target?
This discussion has been closed.