Prius out to race track, 15mpg

Discussion in 'Gen III 2010+ Prius Fuel Economy' started by Bellwilliam, Nov 8, 2010.

  1. Bellwilliam

    Bellwilliam New Member

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    yesterday during the down time (on track running my Spec Miata), took my Prius out for 1 session.

    Track - Street of Willow CCW
    lap time - 1:45.6x (fastest Spec Miata can do it in 1:28).
    MPG - 15mpg
    tire pressure - 36 / 48 cold, roughly 41 / 53 hot. Bridgestone Eco**** tire didn't chunk
    balance - surprisingly good. little understeer. car will tuck in with a throttle lift. may be it is because the tire pressure trick.
    brakes - again surprisingly good, better than many so called performance sedan. A little too much initial bite. braking deep wasn't a problem. stock pads held up find.
    weight - ran with full weight, including spare tires and tools. plus a passenger. It doesn't roll as much as thought, guess may be because battery is down low ?

    Did just a few laps. confident it will do a sub 1:40 with good tires, minus passenger, spare tires, tools. If only I can turn off VSC, and find a way to charge up the battery.

    again, very surprised with its handling and braking. VSC kicked in and beeps every corner. a bit annoying.

    hopefully I set a record for lowest MPG !!!
     
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  2. 2k1Toaster

    2k1Toaster HID Guru

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    For lowest mpg over 2 minutes, anyone that lives up a mountain has you beat. :)

    Easily 8-10 mpg up the slope.
     
  3. cwerdna

    cwerdna Senior Member

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  4. house

    house Junior Member

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    Very cool stuff!
     
  5. spiderman

    spiderman wretched

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    What was the max speed and the lap average?
     
  6. Blackmamba

    Blackmamba New Member

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    Its amazing you can get 15 mpg on the track, but once your out on the street again your back at 50-60mpg. Aint this car great?
     
  7. xs650

    xs650 Senior Member

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    I was tempted to ask if I could run a session in my Prius when I did a track day at Thunderhill a couple of months ago but didn't.

    Thanks for the report.:cool:



     
  8. Bellwilliam

    Bellwilliam New Member

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    Street of Willow of Willow Springs Raceway

    it is a tight track. This is the track that last issue of Motor Trend did a comparison test of M3 vs. Mustang GT. both turned 1:28s.

    top speed was 88MPH. average speed at 1:45 is 61MPH.
     
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  9. drees

    drees Senior Member

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    Good tires and an alignment should shave 5 seconds off easily. Do you have lap times for other stock vehicles?

    I'd guess that you'll find that with sticky tires/alignment you'll want stiffer sway bars...

    You can charge up the battery by holding the brake and gas pedal while at a stop.
     
  10. Bellwilliam

    Bellwilliam New Member

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    that doesn't count. lowest MPG is parked and engine on. ZERO MPG.

    that was also not 2 minutes. it was a 20 minutes session.
     
  11. Bellwilliam

    Bellwilliam New Member

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    thanks for the tip on battery charging.

    on stock tires
    stock 1st gen Miata - 1:38s
    stock S2000 - 1:29s
    stock latest gen M3 - 1:28s
    stock latest Mustang GT - 1:28s
    Spec Miata record - 1:28s

    note this is the track record for these stock cars on stock tires. I am a track driving instructor and a Spec Miata driver. I am pretty sure I can do a sub 1:40 just with good street tires and no passenger.
     
  12. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    Sounds like it's time for R-comps. :) No more VSC warnings.
     
  13. drees

    drees Senior Member

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    If you get the 17" wheels/tires from the Prius IV - does that still count as stock? They should be a bit better than the 15" tires though the weight of them will hurt a bit.
     
  14. Bellwilliam

    Bellwilliam New Member

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    I would prefer something like 15x7 (is this the widest that would fit ?) wheel and 205/50-15 StarSpec, instead of 17". less unsprung weight. but this really won't be stock any more. or 195/50-15 R1R on stock 15" wheels, that would work well.
     
  15. drees

    drees Senior Member

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    7" wide wheels should fit without issue - lots of people are using them.

    Any wider and you might need to roll the fenders. :)

    15" I agree would definitely work better for the Prius - it needs all the weight reduction it can get.

    I wonder what kind of alignment numbers you can get out of the stock equipment - with camber bolts you can probably get plenty of camber up front - enough to dial out the understeer - though it might increase wheelspin coming out of corners on the inside tire if you're already seeing some...

    Nice thing about the Prius is that it will hold your track wheels/tires without any problem. :)
     
  16. Bellwilliam

    Bellwilliam New Member

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    took it out to track again today. this was my 1:45.7 lap. best lap was 1:42.9 w/o passenger.


    still on stock 15" tires. this time I got 14mpg, must be the winter fuel.
     
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  17. xs650

    xs650 Senior Member

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    Thanks for the video and verifying my impression that a stock Gen III has pretty decent handling.

    What kind of reactions did you get from the other drivers?

    How did you choose your tire pressures and what pressures do you use on the street.

    Please keep the track stuff coming.
     
  18. Bellwilliam

    Bellwilliam New Member

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    I ran 40 hot front, 55 hot rear. ran rear much higher to help it rotate. I did ran front higher than normal, to help with chunking of front tires. I didn't bother using a pyrometer, cars has no camber anyway.

    many were cheering on over the pit wall, especially when I passed someone (10 cars or so). to be fair, I was an instructor, so I took ~8 students out in the Prius. I took them out in beginner group, so it was easy to pass.
     
  19. F8L

    F8L Protecting Habitat & AG Lands

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    Very cool! :) I need to video my canyon run sometime.
     
  20. xs650

    xs650 Senior Member

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    I figured that would be the response at a track day.:rockon:

    Do you have any interest in taking it further...better tires, more camber?

    If any of those beginners doubted that the driver was more important than the car, I suspect they got rid of that doubt.