Trying to hypermile

Discussion in 'Start Your Journey Here' started by Mad Hatter, May 13, 2008.

  1. Mad Hatter

    Mad Hatter Active Member

    I drive an 02 Jeep Grand Cherokee 4x4 automatic. I am trying to get more mileage out of it. I have read the beating epa estimates and reading as much as I can on here about hypermiling techniques. The jeep has computer that tracks average MPG, 2 trip counters, instant MPG, and outside temp. I pretty much keep an eye on either average or instant MPG.

    The daily commute consists of some congested interstate and city driving. I drop my kids off at school which accounts for city driving or my commute would be just about be all highway. Approximately 10 miles total one way.

    Getting on interstate is always backed up and congested. I pretty much try to keep moving in merge lane until out of road. I can usually slip in an opening as traffic is stop and go. Then its stop and go for about half mile before opening up with better flow with speeds around 55. About 5 miles then I get off interstate and hit 2 red lights before going up hill with stop sign every block. After dropping off children I have more stop signs and traffic lights. The lights are timed well so I only have to stop at one if at all. I then travel up and over a small bridge with nice downhill to a red light. Sometimes I can shift to neutral and FAS just before going up and over the bridge down to red light. Other times I just shift to neutral and glide. The rest of the way is several stop lights. At least one is a light at bottom of hill and I can FAS glide to a stop.

    I'm just wondering if doing FAS is ok on engine and transmission? I'm figuring that its such a short time period that it shouldn't hurt if no oil is pumped to lubricated parts.

    I'm also wondering if doing NICE is putting more wear on transmission? I mostly do NICE when I know my speed will decrease below 30 mph. If I NICE at higher speeds the transmission hunts for the proper gear for that speed. So pulse and glide, NICE at highway speeds doesn't work for me. I can do pulse and glide without NICE but with these all terrain tires it doesn't seem to help. Speed drops immediately.

    What is a good acceleration for doing pulse and glide? Do you accelerate quickly, slowly, or in between to your max speed? I try to keep RPMs below 2000.

    I did pump up tires to 38 psi which is above max on sidewall of 35 psi. That seemed to give me about half a MPG on this last tank. I also had a recent oil change so that is good.

    Any other suggestions? I would ride my bike if I didn't have to shuttle my children to school. I am also looking for a new ride. Considering a new prius, HCH, or Vibe. Also considering a used car like a Civic or something. My mechanic brother-in-law says hybrids are not good but he doesn't work in the auto field any more and he says go with diesel. I think diesel costs too much and you either have to buy truck or compact car.
  2. theLimeyBrit

    theLimeyBrit Padawan

    Since you're driving an automatic, consult your owners manual about FAS. If you can flat tow the vehicle, you're good to go. If not, there's probably a line in there somewhere that says to avoid flat-towing for more than ~50 miles or at speeds higher than ~35mph.

    NICE-on gliding shouldn't hurt your transmission any, but I've never experienced my transmission trying to hunt for the proper gear, so I dunno 'bout that one.

    The best technique I've found on my auto Regal is DWL.
  3. geekbanter

    geekbanter Member

    May car seems the same way about wanting to hunt for a gear. If you keep trying to P&G you will learn to anticipate what your vehicle will do, and you will be able to know when to shift, rev match, and keep the transmission from shifting. At least if your jeep cooperates! :p What I have found through my scanguage is that in my car that cruise control will give better mileage than keeping a constant load. May be some way the chip in the Focus is set up. YMMV.

    For FASing, I do occasionally in my car if I know I'll be stopping at a red for a while. My car manual states it can be flat towed at less than 35mph for less than 25mi. Whether this is good for it, I don't know. I really wish my car was a stick... :(

    BTW, is there any way to avoid all those stop signs on your route?
    Last edited: May 14, 2008
  4. Mad Hatter

    Mad Hatter Active Member

    Thanks, I forgot to mention I try DWL and DWB as much as time permits.

    Thanks for the reply. I'm not a big fan of cruise control because it seems to waste more gas by trying to maintain speed over hills and overpasses. I will ease up going over hills and overpasses DWL. It wouldn't work well during the rush hour drives either.

    Only way to avoid the stop signs would have me sitting at more stop lights. I might try it but if I recall the timing on those lights is off. I did change route after drop off because I found better one that has better signal timing.

    I did FAS at one light today that was red for 2 minutes 31 seconds. I grabbed a stopwatch and have started timing stop lights just out of curiosity. I was at top of hill and saw light change red and did immediate FAS and glided to stop.:)
  5. ascribe2thelord

    ascribe2thelord Recreational Hypermiler

    My best suggestion would be to turn the engine off on downhill grades in stop-and-go traffic (you can use the emergency brake or the regular brakes to slow yourself) and to get out of the stop and go routine in favor of "slow and slow".

    The main place where you can save gas right away is in the realm of city driving. Highway hypermiling can be done, but this requires mastery of techniques that hybrids are designed to make much easier.
  6. Mad Hatter

    Mad Hatter Active Member

    I read the manual and the Jeep can be flat towed behind motor homes. However, the manual says to put the transfer case in neutral as opposed to the transmission. In order to do that the engine must be off. Since it is 4x4 putting the transfer case in neutral dis-engages both front and rear drive shafts. The manual says to put the transmission in park and tow.

    So I'm still questioning whether or not doing FAS in neutral will damage anything? The manual states the towing is recommended on a flat bed but towing with either end off the ground is acceptable. So it doesn't sound like it would hurt.
  7. theLimeyBrit

    theLimeyBrit Padawan

    Hmm, if it was my car and the manual didn't explicitly say that flat towing in neutral is okay, I'd err on the side of caution and FAS only at low speeds (<20mph) if at all. Saving a few bucks worth of gas is a bad trade for screwing up your transmission.

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