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What is everyone's opinon ?

Discussion in 'Gen 2 Prius Main Forum' started by ReneGS, Jul 23, 2005.

  1. ReneGS

    ReneGS New Member

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    How do most of your accelerate from a dead stop? When I slowly creep up to speeds I'll have read outs of single digits MPGs. Am I really only getting 5mpg when I slowly take off from a light?

    I read several replies to another post where people stated that its best to "briskly" accelerate up to speed. Now I know that doesnt mean to floor it. I'm just curious why (if its accurate) I am getting 5 MPGs when I accelerate very sslowly Another thing II'venoticed is that driving 55mpg or 65mpg doesnt make much a difference. Actually I do get home a little later. :D

    My daily commute consists of approx. 200 mile round trip. [​IMG] I pretty much keep the cruise control at 75mph. About 30 minutes into my commute I get a long steep incline. I'll let the cruise control keep me at 75mph. I also use the A/C pretty much the entire time.

    My best MPG per tank has been 43.3mpg. II'vebeen refueling on average 10.9 gallons each time. II'vegotten close to hitting the 500miles mark but keep coming up short.

    Anyways I am close to hitting 2000 miles. IMO I'm averaging pretty good MPGs considering the steep grade I drive up (Driving down it is great!) as well as dealing with 100+ heat.

    Whats everyone else think?

    Rene
     
    #1 ReneGS, Jul 23, 2005
  2. ceric

    ceric New Member

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    IMHO, my Prius is not very efficient at 75mph (around 45mpg) when maintaining constant speed at flat terrain. However, if I slow it down to around 65mph, I could get 51mpg easily without much effort. It is a trade-off really on your part.

    Acceleration: I heard someone said that you should accelerate as fast as no digit is skipped on your MPH display. I personally has no scientific evidence which way is better, though.
     
    #2 ceric, Jul 23, 2005
  3. bruceha_2000

    bruceha_2000 Senior Member

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    First, you need to move - 100 miles one way to work?!?! YUCK!!!!!!

    I think the best "repeatable" description is one that came from Dr. Fusco: Accelerate such that you are neither charging nor discharging the traction battery.

    You will ALWAYS start on electric so don't creep along waiting for the ICE to kick in. There is an interesting balance. If you accelerate faster, you are covering more ground per second than if you accelerate slowly. You can find the point for your roads where you actually get worse MPG by accelerating too slowly. Likewise, too fast will also show up.

    75 MPH WILL run your mileage down. I have driven over 200 miles non stop at 68 MPH. Plenty of hills including the highest point on I-89 (I know, it isn't exactly Angel Pass in CO) and average 49.5 MPG.
     
    #3 bruceha_2000, Jul 23, 2005
  4. efusco

    efusco Moderator Emeritus
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    I've been a little misquoted there.

    I accelerate what can only be called briskly. Not hard, I don't push the pedal to the floor, but I don't baby it either. I'm usually the fastest one off the line unless there's a kid in a hot rod next to me or something.

    Once I get to ~35-40mph I do back off and try to get into the 'dead-band'--no arrows to or from the battery and I try to keep it in that zone as I continue to accelerate.

    But honestly, if you have a 200mile commute the least of your mpg worries is how you accelerate. If you can temper your speed a bit it will make a measurable impact on your mileage...even backing down to 70 or 72 will improve your numbers noticably. But that may not be practical and may extend your trip by about 10 minutes each way. The choice is yours.

    I would make sure that you have the AC set at a comfortable temp, but no colder than you really need it. I find 79 degrees very comfortable as long as the vents are pointed directly at me. Maybe even close the passenger vents off completely to increase the flow through your own vent.

    Also, be sure to have the alignment checked...it is frequently out after shipping. Just tell them you're not getting the expected gas mileage and/or you're feeling like the handling isn't quite right and the dealer should do it for free.

    Be sure your tire pressures are around 42f/40r...if that's too high I'd at the very least increase them to 40f/38r--check them when cold and have a pump handy to get them just right. I promise you that that tire pressure will make a measurable difference with a commute like yours.

    Get rid of any excess weight in the car. Even if you can get rid of 50 lbs it'll make an incremental difference.

    Draft, at a safe distance, when you can. If you watch the energy screen when you're drafting at 75mph vs when you're breaking the wind yourself at that speed and you'll notice a dramatic jump in your mpg display. Very noticable on the consumption screen too. Drive along for 15 minutes post warm-up at 75mph not drafting....then jump in behind a big-rig...maybe 2 seconds back for 15 minutes and notice that the first 3 bars will be notably lower than the second 3.

    All that said, 43mpg for 75mph ain't bad considering. I think you can do a little better, maybe upper/mid-40s by trying the above techniques.
     
    #4 efusco, Jul 23, 2005
  5. silentak1

    silentak1 Since 2005

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    efusco has provided EXCELLENT feedback.

    I'd like to add that you may also...

    1) Apply wax to the car (it may not even give you 0.5mpg more...) but anyway it's good for your car.

    2) AC must be above 74 (preferribly 76+). I find that 74 and lower usually consumes more battery.

    I find it VERY helpful to run the tires at 42F/40R as this decreases drag but makes a bumpier ride.

    BTW, I was also pondering the same question today. I accelerate slowly but my screen shows less than 20MPG.... How do i go about achieving 60mpg or even 50mpg in the city? In the 1400 miles driven so far i've been averaging 47MPG or so mostly highway.
    (It is also 90+ degrees outside & I use the AC all the time... I am very happy with 47mpg, but please tip me your tricks)
     
    #5 silentak1, Jul 24, 2005
  6. mehrenst

    mehrenst Member

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    IMO, one of the issues concerning mileage and acceleration is that when the ICE starts it tends to run in a range of RPMs. I believe that the trick on acceleration is to make optimum use of the ICE rpm without causing it to increase unnecessarily.

    Its hard to tell without a tach but from listening it sounds like the ICE goes to an initial set speed and then increases as needed. I have to assume that there is some fairly intelligent conversation going on between the ICE management, the VCT management, and the Hybrid management.
     
    #6 mehrenst, Jul 24, 2005
  7. IALTMANN

    IALTMANN New Member

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    Definetly brisk acceleration and good feathering techniques is the way to get good mileage, stop and go situations. Consider negating the AC and use windows, open left one and crack open one on the right if you can AT lower speeds (25-40), early mornings and evenings it's not bad, I'm from Texas and I survive. On the highway at 75 (that may be a bit fast, suggest 67-68) you should keep the windows closed and use the AC, close off right side vents if no passengers, and raise the set temp to about 4-5 degrees below O/S air, but in no case lower then 76, I usually try for 78 degrees, no more because if it is 95 out there you need 78-79, but if it is 79 o/s and you want cooling, set for about 75.

    All of this will improve the mileage, mine went up 4-5 mpg just from doing that.
     
    #7 IALTMANN, Jul 24, 2005
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