Some observations of the Prime at high speed

Discussion in 'Prime Main Forum (2017-Current)' started by Pdog808, Jul 28, 2017.

  1. Pdog808

    Pdog808 Active Member

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    Just did a less than 5 hour trip from Los Angeles to San Jose on the I-5 freeway yesterday.

    I basically drove the Prime in two separate "modes". The first mode was the standard "Prime" way of setting the cruise control to 9 MPH above the posted speed limit (74 MPH) and letting peeps pass you regularly and/or cut in front of you. The Prime handled this well with no issues climbing most hills up until the Grapevine. There is a section on the north bound I-5 climbing up to the Grapevine that is about a 5% grade. I noticed the Prime had a bit of an issue maintaining speed here but was still able to climb at a respectable 60 MPH. For comparison, my V6 Camry can climb it at 75+ MPH. A/C was running on Eco-mode and 74 degrees the whole trip.

    On the back side of the Grapevine, it is basically a 6% grade going downhill. Here I noticed something quite interesting. If you regen battery power on a downhill in HV mode, the vehicle will gain back the energy (in my case 14% regained) but then allow that extra charge to be used in normal HV driving so that the vehicle goes back to the charge level it was at before you started downhill. I wonder if you should put the car into EV mode mode in order to keep the charge level?

    FWIW - I put the car into "B" mode on the downhill section in order to avoid having to use too much braking (didn't want to wander into actual brake pad usage - yikes). The regen gains were quite impressive. At 80 MPH down hill in B mode you can actually see the battery ticking up very quickly.

    The second mode I drove the Prime in was the "I'm tired of getting passed" mode where I drove at speeds between 80 to 95 MPH. The vehicle handled these high speeds VERY well. I expect that the fact that the vehicle is extremely low and has a great coefficient of drag plays a large part. The only issue was a bit of buffeting as you passed 18 wheelers but nothing alarming. Passing other vehicles at high speeds was easily done and acceleration was more than adequate from 70 to 95 MPH. Cruising speed was usually about 85 MPH. This was all in HV mode of course.

    Mileage (estimated) for the high speed driving was about 54 MPG. Not bad. Basically it cost me about $24 in gas to go from Los Angeles to San Jose (about 330 miles). I arrived in San Jose with over a third of a tank left from almost full in Los Angeles.

    Handling - hit the 25 MPH hairpin exit to the 152 highway at over 60 MPH due to getting distracted from the GPS at just the wrong time. Basically braking VERY hard going into the exit and the Prime never drifted or felt like it was going to break loose. Vehicle roll was minimal and I know for a fact that my V6 Camry would have rolled like a beached whale in that turn (not rolled as in rolled over but definitely would have felt "looser"). ABS did an exceptional job especially going into the hairpin curve and it was most certainly engaged. Pretty much decelerated from 60+ to 25 MPH in about 150 feet while in a very sharp right hand curve. Very nice.

    Comfort - probably needed to set the A/C at a lower setting. 74 degrees in Eco mode is OK but it was 106F outside! Softex seats were very comfortable. This was something I was concerned about for long drips.

    We'll see how the Prime handles the 6% grade on the way back to Los Angeles on Sunday!
     
  2. bisco

    bisco cookie crumbler

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    yes, if you want to retain charge for ev mode, the region must be done in ev mode.
     
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  3. ForestBeekeeper

    ForestBeekeeper Active Member

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    I drive at 82mph almost every day. Our prime does well at that speed.
     
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  4. CoastRider

    CoastRider Active Member

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    I'm glad your new Prime handled well. I don't have a Prime, but I find those displays and screens to certainly be distracting at times. Very bad habit to keep looking at those things, and totally unnecessary (for me).

    Isn't it crazy how fast people are driving in California? 85, 90, 95???!
    In my humble opinion, that is just insane! I let everybody pass me, and enjoy a fairly nice relaxing drive. (But I don't drive so slow as to block the flow of traffic. I just drive normally.) The speeding is out of control, I don't know what the answer is but something needs to be done about it. A total disregard for the speed limit laws.

    I sure am thankful I'm retired, and don't have to drive those damn crazy freeways every day. I think people have gone completely nuts. They get behind the wheel of a car, and their whole personality changes, for the worse it seems. Enjoy your Prime.
     
    #4 CoastRider, Jul 28, 2017
    Last edited: Jul 28, 2017
  5. Pdog808

    Pdog808 Active Member

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    Well, technically only 90-95 to pass. Usually cruising at 85 or so. If you drive 70 MPH in the slow lane you'll be overtaken by most 18 wheelers.
     
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  6. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    In regards to "not maintaining speed" up the hill was your foot to the ground? Because if not, then you had power you just chose not to use.

    Reason I ask is because in our GenII with a much much much smaller battery, the only limiting factor that makes it difficult to go up 5% and 6% grades (I-70 through Colorado Rockies, steepest interstate in the country) is when the battery is low and you are adjusting speed too much.

    For these grades, you mash the pedal and you go. The 2006 with a failing pack was able to maintain 82mph up the 6% grade sections with the 1-bar battery, so only engine power. In the Prime you have a larger battery and larger engine so you should have no problem. When one of my coworkers in his Prius did the same drive he also had the car seemingly limit him to 55-60 mph up these hills. But he was constantly adjusting his foot up and down on the accelerator and the engine take a long time to spin up fully, so basically it was never at full output power, hence the lower speed. He was convinced his car was broken so after he showed me his drive up the passes and sure enough we just got slower and slower until we had to get into the crawler lane, I drove his car on the same pass back and then again on the same section. Maintained over 80mph the entire time.

    Prius on 5% or greater incline = mash your foot to the floor. If you need to slow down, blip it off and mash again. That will be enough to slow it down and the engine takes another few seconds to come back and again your increasing in speed.

    If the Prime actually has a mountainous accent problem, that could be true. I've never driven one unfortunately. Just curious what your foot movement looked like.
     
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  7. Pdog808

    Pdog808 Active Member

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    Actually that is a valid point. I had the pedal floored at times but mostly at 80-90% depression. It just felt as if the vehicle hit a wall at about 65 MPH at the steepest part. I had about a 69% battery charge on the uphill. It may have been possible to get more speed if I kept the pedal completely floored the whole way but prefer not to drive that way for extended periods (and the hill is at least 2 miles long, maybe longer).

    I'll see how the vehicle does on the 6% grade going back on Sunday morning. That grade is where you see at least 2-3 cars pulled over to the side due to overheating. 18 wheelers crawling up the grade at 35 MPH also.
     
  8. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Keep in the mind the Prius does not "redline" like convention autos. The engine spinning at full pedal depression is still well within limits and can be held there indefinitely without cause for concern. The Prius is a glorious machine.

    Another thing is I believe you said you were in ECO mode. What this actually does is remap your pedal input to power output. In the Toyota hybrids it is distinctly different than their Lexus counterparts. At all times, your Toyota Prius has the same exact amount of power available to it assuming there is battery charge available. When you put it in ECO mode, what you're doing is giving a greater range of your pedal to much lower power output requests. In the sport mode, all it does is make a greater range of the pedal input translate to the higher power output. In any mode, if you mash the pedal to the floor, the output power will be exactly the same, the 0-60 will be exactly the same.

    So if you're driving in ECO you are also giving up most of the power section of the pedal and if you want power you will have to mash the pedal to get the power out.

    And yep our hills here are always strewn about with overheated vehicles and the run-away truck ramps are used more frequently then you'd think. I can't even count the number of car's, well mostly SUVs with out of state plates, I've seen going down the hills and their brakes are literally smoking and glowing.

    The only hill I have trouble ascending at full speeds is Pikes Peak. Once you get up to 12k feet and you still have steeply graded roads with tight switchbacks, there is almost not enough room to get power up before the next tight turn and there just isn't air. Up at the top at 14k feet lots of vehicles can't get started back up again lol. Got to love the Prius, it is an awesome mountain goat. And you can wave at all the other cars parked at the mandatory brake temperature check-point on the way down thanks to the regen brakes.
     
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  9. bwilson4web

    bwilson4web i3 and Prime

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  10. ForestBeekeeper

    ForestBeekeeper Active Member

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    The interstate where I live [I-95] is posted 75mph. I drive on it every day. Traffic here on the East Coast is commonly 80-90mph.
     
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  11. ForestBeekeeper

    ForestBeekeeper Active Member

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    The interstate where I live [I-95] is posted 75mph. I drive on it every day. Traffic here on the East Coast is commonly 80-90mph.
     
  12. JamesBurke

    JamesBurke Senior Member

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    I think power may have been reduced do to the 106f+ac+hill climb. Safeguarding the power electronics and battery. Southbound climb is much more demanding than the Northbound climb. 3200ft in 15 miles with a constant slope.

    grapevine.jpg
     
  13. CoastRider

    CoastRider Active Member

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    I was descending a long winding hill of 3 to 4 miles, and I tried the B-mode. It seems to work fairly well, but it didn't really slow me down that much. I still had to use the brakes to reduce speed. (Actually, I had to ride the brakes quite a lot.)

    The gas engine starts racing really loud when I used B-mode. Is that normal? I was expecting to see Pistons shooting through the hood! :ROFLMAO: I'm still kind of confused about what the purpose of B- mode is for. I can't downshift the transmission like in a regular car, and I want something to help slow me down.
     
    #13 CoastRider, Jul 29, 2017
    Last edited: Jul 29, 2017
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  14. Lee Jay

    Lee Jay Senior Member

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    That's what B-mode does. It works about as well as most modern four-cylinder cars shifted down. For example, it's about as strong at 55mph as my Mazda5 is shifted from 5th gear down to 3rd gear at the same speed.
     
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  15. CoastRider

    CoastRider Active Member

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    Thanks, but my Prius doesn't seem to react that way. While going down the long hill, my car didn't seem to slow down at all, if any. And is it normal for the gas engine to race like that?
     
  16. Lee Jay

    Lee Jay Senior Member

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    I drive down a 6% grade every day I go to work. B-mode causes the speed to decrease on that stretch.

    That's the whole point of B-mode in Hv - it spins up the engine to provide engine pumping losses to add drag to the wheels. In Ev, it just regenerates, but the power is about the same.
     
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  17. CoastRider

    CoastRider Active Member

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    Thanks Lee. I'm going back up to that area again tomorrow, I will practice using the B mode. Something doesn't seem right, as my car is not really slowing down.
    And the engine noise was so loud, I was thinking it was going to do some damage.
     
  18. joachimz

    joachimz Senior Member

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    I've done that trip over the Grapevine many times in my Gen3, only once with the Prime but typically going 75-80 on that uphill (when traffic allows). Never felt that I am "short of" power, actually amazing imho how both Gen3 and the Prime perform on that climb.
    And on that one trip with the Prime, I regenerated ~11 miles on the 6% downhill, it was painful in the Gen3 once the battery was charged how the ICE was whining on that downhill in B, but in the Prime, it was awesome, had the CC at 65 and it kept charging and charging ... and I kept it in D, and I always drive in ECO
     
    #18 joachimz, Jul 29, 2017
    Last edited: Jul 29, 2017
  19. heiwa

    heiwa Active Member

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    I find D with cruise control set to a speed in eco mode the best when going steep downhill so long as turns do not require change of speed. Prime will swtich to EV and increase regen to control speed or spin ICE as needed.

    Posted via the PriusChat mobile app.
     
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  20. joachimz

    joachimz Senior Member

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    agreed, edited my post above and included that.
    Disclaimer on my agreement: 2 lane why might be a different story though ...
     
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