1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Does the 4th Gen. decelerate faster on its own than 3rd Gen.?

Discussion in 'Gen 4 Prius Technical Discussion' started by Michael Bluejay, Jul 7, 2017.

Tags:
  1. Michael Bluejay

    Michael Bluejay New Member

    Joined:
    Jul 7, 2017
    5
    5
    0
    Location:
    Austin, TX
    Vehicle:
    2017 Prius
    Model:
    Four
    On my 2011 Prius, when going down a hill I'd turn off the cruise control to save energy by preventing the regenerative braking. (Putting energy into a battery and getting it back out again is inefficient; there's an energy penalty in each direction. The Prius lets you re-use *most* of the energy from braking, but not all.)

    Anyway, going down a certain hill in the 2011, I'd typically gain 5-6 mph in speed from the top to the bottom. In my new 2017, I gain only about 2 mph. Also, on level roads when I take my foot off the Go pedal it seems that the Prius slows down a lot faster in my 2017 than the 2011.

    For other 3G > 4G owners, has your experience been the same or different?
     
    #1 Michael Bluejay, Jul 7, 2017
  2. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    45,024
    16,242
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Paid closer attention today. Cross a suspension bridge that has a long descent on one side. On my Gen 3, it will slowly gain speed with my foot off the accelerator while on the Gen 4, it gained speed much, much more slowly such that I was able to maintain near the speed limit through most of the descent (while on the Gen 3, I would be riding the brake and regen'ing that way).
     
    #2 Tideland Prius, Jul 9, 2017
  3. Michael Bluejay

    Michael Bluejay New Member

    Joined:
    Jul 7, 2017
    5
    5
    0
    Location:
    Austin, TX
    Vehicle:
    2017 Prius
    Model:
    Four
    Yeah, I was a little bummed that I lost my favorite trick to eke out a little extra mpg, but on the other hand the MPG in my Ten 4 is so fantastic it's kind of beside the point. I know the official figures are an improvement from 48 to 52 mpg for Gen 3 > Gen 4, but my experience has been going from around 50 mpg (Gen 3) to 60 mpg (Gen 4). I got close to 70 mpg today for about 80 miles.
     
    #3 Michael Bluejay, Jul 9, 2017
    RCO likes this.
  4. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    45,024
    16,242
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Yeah but at least you can control it by gliding (just lightly depress the accelerator) to reduce the regen strength.

    Yup. I got 67mpg (3.5L/100km) according to the trip computer and 60mpg (3.9L/100km) return. There's no way I would've gotten that with my Gen 3.
     
    #4 Tideland Prius, Jul 9, 2017
    Mendel Leisk and RCO like this.
  5. RCO

    RCO Senior Member

    Joined:
    Aug 31, 2016
    3,709
    5,184
    0
    Location:
    Cornwall
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Me, I just drive it how I'm feeling without trying to cruise. If I try to consciously 'follow the needle' the distraction from my driving is noticeable to me. Probably age-related mental deterioration as I don't drink alcohol or use any other substances.
     
    #5 RCO, Jul 9, 2017
    Last edited: Jul 10, 2017
    kithmo and Tideland Prius like this.
  6. Sam Spade

    Sam Spade Senior Member

    Joined:
    Dec 3, 2016
    2,036
    1,023
    0
    Location:
    USA
    Vehicle:
    2017 Prius c
    Model:
    Four
    This makes little sense.

    Unless you "feather" the gas pedal, when you coast down that hill a healthy amount of regen braking is going to occur whether the cruise is ON or OFF. Maybe a bit more with it ON but likely not a lot of difference.
     
    #6 Sam Spade, Jul 9, 2017
    alanclarkeau and RCO like this.
  7. PapaNoel

    PapaNoel New Member

    Joined:
    Apr 14, 2017
    2
    1
    0
    Location:
    Finland
    Vehicle:
    2017 Prius
    Model:
    Four
    I would like to hear more about driving On / Off Cruiser, does it save gas or not?
    I really don't know.
    11'000 km driven.
     
    #7 PapaNoel, Jul 29, 2017
    RCO likes this.
  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

    Joined:
    Oct 17, 2010
    56,664
    39,220
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I'd second that: just step lightly on the gas, reduces the regen drag if needed.
     
    #8 Mendel Leisk, Jul 29, 2017
  9. RCO

    RCO Senior Member

    Joined:
    Aug 31, 2016
    3,709
    5,184
    0
    Location:
    Cornwall
    Vehicle:
    Other Hybrid
    Model:
    N/A
    It will all depend on your driving style and the terrain. Your best economy come from driving it smoothly like a regular car allowing the speed to vary as the gradient demands. When you use cruise control, it will do our utmost to keep to the set speed and unless you're driving along the flat (?) you will see the fuel burnt increase. There is not a great deal of difference for me as a rule but your mileage may vary (YMMV).
     
    #9 RCO, Jul 30, 2017
    kithmo likes this.
  10. kithmo

    kithmo Couch Potato

    Joined:
    Apr 25, 2010
    2,404
    2,773
    47
    Location:
    South Yorkshire, UK
    Vehicle:
    2016 Prius
    I would say that most of the time cruise will be less economical, but also less stressful. Trying to eek every last mpg out of the car is sometimes fun, but on a long journey I personally find it tiresome and hard work, I'd rather set DRCC and let it do it's thing.
    I generally get around 65 mpg (UK gallons) using DRCC on a mix of A roads and motorways where I have managed around 75 mpg without trying to drive economically, just keeping up with traffic, not using DRCC.
     
    #10 kithmo, Jul 31, 2017
    RCO likes this.
  11. 01prius190K

    01prius190K Junior Member

    Joined:
    Jul 20, 2010
    15
    9
    0
    Location:
    Conesus, NY
    Vehicle:
    2016 Prius
    Model:
    Two
    I believe one of the design changes of the G4 wa a less restrictive CVT. but it depends on how you drive with respect to limiting the regen on downhills. I prefer to goose it a little going downhill to gain lots of speed and maintain pedal position to let speed decay back to something reasonable on the up. I think driving in normal mode gives more accelerator pedal feel to control regen. Just my opinion...
     
    #11 01prius190K, Aug 25, 2017
    RCO likes this.
(You must log in or sign up to post here.)