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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: hp@rpm = 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: 12,687
    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).

    2013 Civic SI, 2009 Outback Sport 5-spd (stick)

  • 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: 9,614
    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.
  • 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: 12,687
    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.

    2013 Civic SI, 2009 Outback Sport 5-spd (stick)

  • 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: 12,687
    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.

    2013 Civic SI, 2009 Outback Sport 5-spd (stick)

  • 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: 12,687
    aren't the CAFE standards already fairly pathetic? Lower them 20% and you might as well just cancel them entirely.

    2013 Civic SI, 2009 Outback Sport 5-spd (stick)

  • 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.
This discussion has been closed.