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Improved MPG by removing seat

Discussion in 'Gen 2 Prius Fuel Economy' started by zenMachine, Jul 25, 2007.

  1. zenMachine

    zenMachine Just another Onionhead

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    I took the passenger seat out last weekend to work on the JBL amp and decided to leave it out for a few more days until I'm finished. Lo and behold, my average MPG shot up from 46 to 52. At first I didn't know why. But it finally dawned on me that the removed seat must have contributed to it, despite the fact that I've added more weight to the car (new amp, SD mats, etc.).

    Don't know how much that seat weighs, but it sure makes a huge impact. Reminds me of the story of some Japanese hypermiler who did that to his car. Hmmm.... Wonder if the wife will like this... :)
     
  2. Danny Hamilton

    Danny Hamilton Active Member

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    I've wondered about this a few times. I use my car almost exclusively for commuting alone. I rarely have any need for the passenger or rear seats.

    Just how difficult is it to remove the passenger seat and the backs/cushions of the rear seats?

    Just how much weight could I drop from the car by doing so?

    Anything else nonessential I can leave in my garage?

    I probably wouldn't bother removing the seats if it was going to take more than 15 minutes to replace them (for the occasional time when I need to accommodate passengers.
     
  3. berylrb

    berylrb Member

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    <div class='quotetop'>QUOTE(zenMachine @ Jul 25 2007, 04:45 PM) [snapback]485001[/snapback]</div>
    Zenmachine, did you notice any increase in the ambient temperature of the car, I wonder if we're talking not just about weight, but a general cooling of the battery compartment through convection (e.g., A/C), hmmm?
     
  4. zenMachine

    zenMachine Just another Onionhead

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    <div class='quotetop'>QUOTE(berylrb @ Jul 25 2007, 04:50 PM) [snapback]485006[/snapback]</div>
    Wow, your question went right over my head. I use very little A/C in the car anyway (almost always on Low) so I really can't tell you.

    The big noticeable thing for me was that I now hear much more of the right rear speakers, so I have to fade forward and left a few notches to maintain acoustical balance.
     
  5. zenMachine

    zenMachine Just another Onionhead

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    <div class='quotetop'>QUOTE(Danny Hamilton @ Jul 25 2007, 04:49 PM) [snapback]485005[/snapback]</div>
    The rear seat cushion is a snap to pull out. Less than a minute. But it's very light so I'm not sure you'll save much by doing that.

    The front seat is not too bad. Now that I've done it a few times, I can probably take it out in less than 15 minutes, and put it back in less than 10. Removal takes a bit longer because you have to unplug the wiring harnesses. Takes some practice. Snapping those harnesses in is much easier, of course. The trick is to unbolt the four big bolts, tip the seat backward so you have room to work on the wiring harnesses. A small flathead screwdriver is very useful.

    Also, if you're cautious like me, you'd want to disconnect the 12V battery in the rear first to prevent accidental activation of the side airbag.

    I don't know the exact weight of the front seat, but I know it's not light.

    Without the passenger seat, the car feels like a big van. If you have an occasional passenger, I think they'd enjoy sitting in the back with all that leg room! I was thinking of putting a small pillow over the JBL amp so that a passenger can rest his/her feet on there, stretch out, relax, and enjoy my pimped ride. :)
     
  6. Danny Hamilton

    Danny Hamilton Active Member

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    <div class='quotetop'>QUOTE(zenMachine @ Jul 25 2007, 05:20 PM) [snapback]485029[/snapback]</div>
    What about the folding seat backs on the rear seats? Easily removable? Light/Heavy?
     
  7. zenMachine

    zenMachine Just another Onionhead

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    <div class='quotetop'>QUOTE(Danny Hamilton @ Jul 25 2007, 05:23 PM) [snapback]485031[/snapback]</div>
    Good question. Don't know.

    I didn't have to mess with them when doing my amping and damping, so I didn't even look.
     
  8. darelldd

    darelldd Prius is our Gas Guzzler

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    Six mpg gain by removing a seat and adding weight back in? Yikes... you don't REALLY think it is the removed seat causing this gain, do you? Over how many tanks? How are you measuring it?

    It would seem that if we all went on a diet and lost a few pounds that we could all gain six mpg. Or even easier, just don't fill the gas tank all the way. Leave it two gallons down and you'll get the same benefit. When I overload my car with four passengers and gear, I lose one or two mpg at most. That's with the addition of maybe 800 pounds over normal. Call me a skeptic... but really, I can't figure out a way to make a seat removal = six mpg.
     
  9. Malarkey

    Malarkey New Member

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    <div class='quotetop'>QUOTE(darelldd @ Jul 25 2007, 06:38 PM) [snapback]485035[/snapback]</div>
    I saw a stat about three months ago that listed how many gallons of gas per year were used to transport the extra weight people have. It was a huge number.
     
  10. zenMachine

    zenMachine Just another Onionhead

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    <div class='quotetop'>QUOTE(darelldd @ Jul 25 2007, 05:38 PM) [snapback]485035[/snapback]</div>
    For as long as I've been driving this car, I have NEVER been able to hit 50mpg. The best ever for me so far was like 48. So I was quite puzzled at first by this strange phenomenon. I initially thought it was due to the warmer weather. But I don't think that should have this big an effect. I could be wrong.

    I plan to keep the seat out at least a few more days to verify that it's not something else. I'm pretty sure the weight differential is pretty significant. The dampening stuff is at most 12lbs so far. The amp is only a few lbs. at most. Whereas the seat is probably around 60lbs (I'm guessing here).
     
  11. chuck kershner

    chuck kershner New Member

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    <div class='quotetop'>QUOTE(Malarkey @ Jul 25 2007, 07:03 PM) [snapback]485051[/snapback]</div>
    I AM SO PLEASED to know there are other Prius owners who are getting mid- to upper-40s mpg. When I first joined this group, I was stunned to read amazing 60 and 70 mpg reports, with screen displays to boot, while I was doing around 42-45, up to a one-time high of 52. Today, I'm happy with the mileage my '06 gets, but dred winter, when it sometimes plummets into the mid-20s in -20 F all-night in the cold temps.
     
  12. darelldd

    darelldd Prius is our Gas Guzzler

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    <div class='quotetop'>QUOTE(zenMachine @ Jul 25 2007, 04:09 PM) [snapback]485054[/snapback]</div>
    Warmer weather has much more potential to improve mileage, actually. Is your improvement over several full tanks, or are you just talking about a daily difference?

    Even if the difference were 60 pounds, that is an insignificant percentage of the weight of the vehicle! It would stagger me to find that it makes any detectable difference!
     
  13. chuck kershner

    chuck kershner New Member

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    <div class='quotetop'>QUOTE(zenMachine @ Jul 25 2007, 07:09 PM) [snapback]485054[/snapback]</div>
    Posted to the wrong comment earlier (repeat to the right one): I AM SO PLEASED to know there are other Prius owners who are getting mid- to upper-40s mpg. When I first joined this group, I was stunned to read amazing 60 and 70 mpg reports, with screen displays to boot, while I was doing around 42-45, up to a one-time high of 52. Today, I'm happy with the mileage my '06 gets, but dred winter, when it sometimes plummets into the mid-20s in -20 F all-night in the cold temps.
     
  14. darelldd

    darelldd Prius is our Gas Guzzler

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    <div class='quotetop'>QUOTE(Malarkey @ Jul 25 2007, 04:03 PM) [snapback]485051[/snapback]</div>
    And just think of what an insignificant amount of weight that the human cargo adds to a typical car. If we can save energy by losing body weight, imagine what could be possible by getting all the single-driver 6,000+ pound vehicles off the road!
     
  15. Pinto Girl

    Pinto Girl New Member

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    <div class='quotetop'>QUOTE(zenMachine @ Jul 25 2007, 04:45 PM) [snapback]485001[/snapback]</div>
    I'd like to believe that removing the seat was responsible for the mpg gain, but it seems a little much for just that amount of weight, doesn't it?

    Let us know if the increase is temporary or continues from tank to tank.
     
  16. fairclge

    fairclge Member

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    I was going to hold off on my MPG test results, but my MPG on this last tank with about ¼ left to go has gone from about 49 MPG on the last tank and 47 MPG average before that to around 53 MPG now.
    Over the last few tanks I’ve upped the air pressure to 40 PSI in the tires, changed the oil to synthetic at 2,500 miles and this last tank added 92 octane gas.
    I have slowed the driving on the HOV in the AM, because there is not much traffic in southern Va at 6:30 AM on HOV and I have the special fuels plate :p .
    I do not think any one change is making a difference other than slowing the interstate driving from 65 to 60 when I can, but I will keep testing.
    I do not think the seat would make much of a change…
     
  17. SureValla

    SureValla Member

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    <div class='quotetop'>QUOTE(chuck kershner @ Jul 25 2007, 07:30 PM) [snapback]485069[/snapback]</div>
    I totally agree I struggle to keep it at 45 most of the time, and im really happy when it hits above that. Perhaps all these people raging about 60 to 70 have ev buttons?
     
  18. JimN

    JimN Let the games begin!

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    <div class='quotetop'>QUOTE(fairclge @ Jul 25 2007, 08:05 PM) [snapback]485105[/snapback]</div>
    I believe tp makes a difference. You are on the right track. I don't believe the synthetic oil produces any noticeable results but will defer to the oil experts. Using 92 octane on a regular basis is just a waste. The ICE runs fine on 87. If you had contaminated gas adding the 92 would have increased the overall average for the tank and would have helped--once. Steady and slower speed probably made the most difference. You may be able to pick up a couple more mpg by dropping your speed, increasing your tp, blocking your upper grill, and using the EBH.

    The posters with the 60+ mpg averages tend to have these conditions in common:

    Lower speed limits (local roads at 40-45mph)
    EBH (to eliminate the awful 1st five minutes) and blocked grill (to retain heat--ICE runs less often)
    higher tp (42/40 minimum)
     
  19. darelldd

    darelldd Prius is our Gas Guzzler

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    <div class='quotetop'>QUOTE(SureValla @ Jul 25 2007, 05:11 PM) [snapback]485107[/snapback]</div>
    In general, the EV button reduced gasoline mileage. The EV button is useful for many things, but it is not a magic mileage increaser - all energy comes from gasoline, and charging the battery with the ICE before using it for traction power is a net loss of energy.
     
  20. Danny Hamilton

    Danny Hamilton Active Member

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    <div class='quotetop'>QUOTE(SureValla @ Jul 25 2007, 07:11 PM) [snapback]485107[/snapback]</div>
    Nah, just better driving conditions. I get my >50 by driving 95% on the expressway and just using cruise control set exactly at the speed limit (55mph around here) and driving 40+ miles per trip.

    I agree that a 6mpg improvment is more likely due to warmer weather and other factors than removing the seat. I've wodered how much the seats and seat backs weigh and how easily they can be removed (along with other stuff). If you could get 300 lbs out of the car, you'd drop the weight by 10%. As has already been mentioned people see about 1 or 2 mpg change with the addition of passengers and gear.