using ac on the highway

Discussion in 'Start Your Journey Here' started by jonathag, Jun 9, 2008.

  1. jonathag

    jonathag Member

    Been hm for 4 weeks now.

    Still trying to get better at it, but my last tank in my 00 toyota avalon was 35.4mpg, mostly hiway, 5 out of 7 days were hiway, 2 were in town. Car is rated at 21-29.

    That is by far the best I've ever gotten in this car.

    A whopping 602 miles on one tank of gas!

    My best tank before then was around 460 or 470 miles out of a tank.

    My question, on this tank I went no higher than 55mph on the hiway with the windows cracked about 1/4 of the way (in 90+ degree weather it really sucked!)

    I heard that you could actually turn on the ac if you're on the hiway on #1 fan speed and roll up the windows and it's the same difference, any thoughts?

    Also, gonna bump my hiway speed up to 60mph, can't deal with the 55mph, that's 20 mph slower than I used to go! Which will take me to my next thread and another question.
  2. kwj

    kwj I hypermiled this

    Jonathag, just cracking a couple of windows for a little cross flow, won't noticeably affect your MPGs. Running the A/C will.

    When I was a young buck (back when ships were made of wood), I never bought a car with A/C. I got cars with black upholstery and just folded the driver's seat forward when parked, so as not to burn my nether regions when I climbed in. But, I always drove with the windows down - which created drag that I never assessed.

    I usually hate to show up at work soaking wet. On the way home it is not so bad, except my wife won't hug me until I dry out.

    It's another one of those personal decisions. You will save gas, and therefore pollute less, if you can stand driving without the A/C. You will not save as much with the windows down, or with the windows up and the A/C on.

    If saving gas as much as possible is your goal, you know the way. If saving gas is your goal, but not at the expense of comfort, you know the way. We like that you are trying out these techniques, and proving that they work for you. It's up to you (and everyone who hypermiles) to determine their own thresholds.

    Keep your eye on that number at the top of the page, and recognize your contribution. That's awesome, isn't it.
  3. A024523

    A024523 Currently in Training

    Jonathag, I doubt everyone here is willing to sweat profusely for a couple MPG's. When it's 90-95 degrees, I will crack those windows and drinking icy water really helps. An alternative solution, if you are really serious about FE, is to wear an ice-jacket suit like Wayne does. But I don't want to spend money on that, so at 95+ degrees, I will resort to A/C.

    Since the majority of the load comes from the A/C compressor, the fan speed is much less significant. Therefore, I will keep the fan medium to high, and turn the A/C on a few minutes then off a few minutes, just enough to not be uncomfortable. It seems to effect FE less to have it A/C off while going uphill or accelerating, and A/C on only for flat or downhill.
    Last edited: Jun 9, 2008
  4. kwj

    kwj I hypermiled this

    AO24523, some auto A/C units will automatically cut back or shut down when going up a hill, or when the engine power is needed more to speed up or climb a hill. And you are correct that if you wish, that would be a good time to manually shut down the A/C, when you are bound and determined to use it.

    When I was a kid, we lived in Puerto Rico, Guam, and the PI. We did not have A/C, just fans. We lived. So, would a supplemental fan do the job? I've never tried one of those in a car, but I've seen a few.
  5. A024523

    A024523 Currently in Training

    kwj, thank you for the information, because I didn't realize some vehicles have automatic A/C cut-backs under engine load, as mine does not. I like your idea of a supplemental fan as a more effecient solution.
  6. Shrek

    Shrek Kaizen Driver

    Some thougts for A/C:

    Always use A/C with air set to recycle. Crack one window for oxygen supply.

    A/C has a rather constant resistance, which mean that the faster your engine turn the more energy it consumes.

    Better to use A/C when gliding in neutral, as the increased load on the idling engine will give a more efficient idle due to increased load, higher MAP, increased timing advance.

    Maybe try pulse-and-glide with a/c only on the glides?

    Always load the engine during it's high-idle-rpm warm-up period if, especially if you can not utilize all the energy for driving. It will warm up faster and your A/C is for free as the increased load does not increase consumption.
  7. Vooch

    Vooch Well-Known Member

    When you are forced in a situation in which a/c is required (ie your boss or customer rides with you or your future Mother-in-law) - then you can cycle it on and off ( A/C P&G anyone ?)

    run the A/C when going down hills (in glide or anything above 175% EPA)

    turn it off when going up hill or accelerating

    otherwise run the fan w/o the a/c

    you'll get 80% of the cooling with barely any cost.

    BTW - drive with your shoes off, better pedal control & better cooling !
  8. Shrek

    Shrek Kaizen Driver

    A modern car (mine at least) cycles the A/C on and off by itself as required to keep the temperature as requested.

    One should always set the temperature to the coldest, and adjust temp with the fan. Othewise the computer-controlled system would/could run the cooling at max to dry the air, and engine heat to re-heat to your required temperature.
  9. negative_camber

    negative_camber Magician

    I'll keep mine on. If I'm involved in an accident, finding my shoes and putting them on isn't what I want to do before stepping out on a roadway covered in glass and vehicle fluids.
  10. Shrek

    Shrek Kaizen Driver

    If you are worried about that, you might consider staying at home. Driving a car can also be deadly, you know...
  11. negative_camber

    negative_camber Magician

    Ya, sure, I'll stay at home and live in my plastic bubble :rolleyes:

    I guess you're right, I'm just a dumbass for wanting to be prepared. I've been in 3 accidents and 1 rollover (none of these were my fault), and climbing around in my car looking for my shoes would have been a much more sensible thing to do instead of being ready to simply get out of my vehicle and possibly offer assistance to anyone who needs it. I don't know how things are where you live, but around here accidents can be horrible when 2 vehicles collide at 55+ MPH, and "help" (in the form of a police officer or ambulance) is often more than 30 minutes away. The ONLY immediately available help is from someone who stops to help. In my 9 years as a semi truck truck driver, Ive been "first on the scene" to at least a dozen accidents. A couple of them have been fatality accidents, so there was little I could do, but the rest involved very scared people that needed someone with them until cops and an ambulance showed up, usually between 15 and 30 minutes after a 911 call. Another thing I do, which in your mind of coarse would be stupid, is always carry a pair of heavy duty leather gloves to help free myself or others from wrecked vehicles. The gloves make it a lot easier to grab sharp and/or hot objects. Ya, I know, it sounds stupid to you, but a couple people have been thankful that I had the gloves to help remove enough debris from their cars to allow them to crawl out. Another ignorant thing I do is carry a fire extinguisher in my car. It can be useful, and possibly even lifesaving, to put out a fire on a wrecked vehicle or just one that has an engine catch on fire. I had a brake dragging on a trailer once and it caught on fire. I used my extinguisher and two others from truckers that stopped, and put out the fire. I guess it would have been better to just let a truck and trailer worth $105,000 and freight worth $720,000 burn to the ground instead of being prepared.

    I could go on forever, but there is no need to. You have shown me how stupid I really am for simply wanting to be prepared.

    Seriously though, I'm off to a bad start here. If there are many other people like you on this forum, then I have no reason to stay here. I can't stand smart asses like you "If you are worried about that, you might consider staying at home. Driving a car can also be deadly, you know..." You seem like the kind of guy who would rather sue someone for not taking care of you instead of taking care of yourself. You can keep your smartass remarks to yourself and wander around the planet aimlessly and just let me continue to be stupid and prepared.

    I was just stating a simple safety fact that anyone with an ounce of common sense would know, and then you have to suggest maybe I should stay home. Jeez...
  12. A024523

    A024523 Currently in Training

    Can't we all just get along? Shrek's comment was obviously meant to be humorous, but badly misplaced considering your unfortunate experiences. That said, we don't always agree on things, and that's okay. Let's try to keep this forum positive. Thank you.
  13. Vooch

    Vooch Well-Known Member

    Shoes vs. Barefoot driving - my 2 cents

    Its all a judgement call - given your experience with car crashes, I'd say you are acting in a sensible and prudent fashion in wanting to wear shoes while driving.

    In my case, I find my control of the pedal is vastly increased and that outweighs my concern about what happens post-serious crash.
  14. PTDixieGal

    PTDixieGal Can I go fishing now? GOOD

    I don't run my a/c unless my recycle switch is on, at least not now. However, it will be interesting to see what happens in July.

    As for the driving barefoot...I am going to do that this afternoon when I run some errands but probably not tomorrow when I report back to work. Somehow I get the impression my boss might not like that if I'm late trying to find my shoe LOL!
  15. jonathag

    jonathag Member

    negative camber-sounds like you have had some pretty terrible experiences, but please be more polite, I really don't think shrek meant anything at all by their remark. Not many people out there would have ever thought of having their shoes on in case of an accident. We're all here to try and save money on gas, not really thinking about accidents. But most people, a good 99% of people, probably haven't had your experiences and would have never thought about the need to have shoes on after an accident.
  16. MyPart

    MyPart Well-Known Member

    I'm with negative camber on this one... I'll continue to wear my shoes and have a med kit with gloves. I would rather be prepared than save money/gas this way.

    I also found Shrek's comment out of line. If you're going to be sarcastic or have a dry sense of humor, it's best to put in a smiley or something to indicate your humorous intentions.
  17. Stormdog

    Stormdog Well-Known Member

    I drive barefoot all the time. But that's because I'm barefoot any chance I can get. Typically, as long as the weather is warm, my shoes are off the minute I get to my car after I'm done with work and stay off 'till I go to work again, unless I need to go to the store or something.

    I don't know that it gets me any better gas mileage; I just don't like wearing shoes!:)
  18. A024523

    A024523 Currently in Training

    Should we rename this thread Shoes vs. Barefoot driving ?:D
    BTW my shoes are staying on. Maybe we ought to conduct a survey, but I don't know how to do that.
  19. kwj

    kwj I hypermiled this

    Hi Negative Camber. Welcome to the site. Discussion and debate are what fuels this site. We will often have disagreements, but we could avoid calling anyone names, and still get our point across.

    I've often had fire extinguishers in my cars. And fortunately, never had the chance to use them. I usually have gloves in my car also. Might I suggest you simply put a shoe with your gloves, medical kit, and extinguisher. When you stop for an accident, and go for any of these items, well, there's your shoe. No looking around for it. Make it a loafer so you can quickly step into it while you are donning your gloves, and then you are spending not a second more.

    And Shrek, I can agree with adding a smiley face or a (Ha, ha) or something to indicate that you were firmly tongue-in-cheek.
  20. knottriel

    knottriel Member

    I wasn't going to get myself dragged in, but wear what you want. I wear shoes because I was an EMT, and I've had to jump into several situations I didn't expect. I don't want to look for a shoe if someone is injured and I might be able to help.

    Just me. If you're comfortable without them, great. I don't want to run around on a freeway without something to keep my feet from burning (summer) or freezing (winter.)

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