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My Recent Trip: Expressways…ugh, bad mileage

Discussion in 'Prius c Fuel Economy' started by Fahfoofnik, Nov 13, 2013.

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  1. Fahfoofnik

    Fahfoofnik Member

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    Believe me, I'm fully aware that a road trip on the expressways will take a chunk out of a Prius' gas mileage. I didn't think it'd be THIS much of a hit, however.

    Here's my trip details: 3 people (wife + I, she's about 120lbs & I'm 185lbs; my 50lb son who's 8), 5-6 bags/luggage, a small cooler, pillows. The trip: to/from our area to stay at my sister's home in Cincinnati.

    Around 445 miles, round trip. We took a different route one way that added probably about 50 miles or so. I started out the trip with nearly a full tank; just one tick off the fuel meter, it'd gone off the meter the morning on my way home from work.

    Expressways: speed limits ranged from 55mph to 70mph, save the construction zones (usually 45mph, a few were 35mph). So the trip was about 90% or so expressway. I drove around Cinci one day, no more than 20 miles or so in the city…and then stopped in Champaign, IL on the way home & did another 20-25 miles or so in town.

    My driving habits: drove at posted speed limit in speed traps; otherwise, ever more than 5mph over the limit. Used cruise control nearly completely, save for a few hills where I needed to push the pedal down to get up the hill.

    I had minimal climate control; I used the "heat," temp on anywhere from 66F to 69F, sometimes the defroster for a few minutes. Fan speed always on the lowest or second-lowest.

    Always filled up with 87 octane. Here's what I got over the course of the Friday-Monday trip. Stats from the fill up:

    15 11/11/13 296.8 7.02 42.3 3.090 25% [​IMG]
    14 11/11/13 284.9 7.33 38.9 2.999 15% [​IMG]
    13 11/8/13 348.6 7.82 44.6 2.990 25%


    …41.96. That's my mileage.

    Awful.

    About 75% of my driving is usually city driving (before taking this trip), and according to the Prius C's computer, I'd been getting 58mpg on my trip B odometer, and as Fuelly says around 55MPG.

    I tried to be cautious with accelerating and braking, sometimes when merging you have to "floor it" in order to merge, but I kept that to a minimum.

    So I ask you Prius C experts here: should I be happy with this? Or is this (what I deem) crappy MPG normal for 3 people, baggage & expressway travel?
     
    #1 Fahfoofnik, Nov 13, 2013
  2. ztanos

    ztanos All-around Geek!

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    Tire pressure? Did you check to make sure there isn't anything blocking the vent in the back seat?
     
    #2 ztanos, Nov 13, 2013
  3. Fahfoofnik

    Fahfoofnik Member

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    Yes. As a matter of fact, the very day before we hit the road, I took my car to the dealer for the 5,000 mile service. Nothing was blocking the vent, my son sits on a car seat where that compartment is, but he's a shorty so there was nothing on the floor covering the vent.
     
    #3 Fahfoofnik, Nov 13, 2013
  4. ztanos

    ztanos All-around Geek!

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    Did they adjust your tire pressure? Did you check it after?
     
    #4 ztanos, Nov 13, 2013
  5. Fahfoofnik

    Fahfoofnik Member

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    No I did not. On the several print outs I received from the dealer detailing what was done to my car, there was a checkmark next to something like "Checked/adjusted tire pressure."
     
    #5 Fahfoofnik, Nov 13, 2013
  6. sisharp

    sisharp Member

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    Don't worry about it. With the colder temps this is normal. The heater doesn't affect much since you were driving most of the time. Having the heater on in city driving would drop your mpg since the engine would try to keep warm. Anywho, with the added weight, that also drops the mpg since the engine works harder.

    By driving around 5 over you use more gas right there.

    By using the cruise control, the engine always try to maintain the speed and if there were any hills along the way which you didn't add gas to, then the engine just mashed it for you to maintain say 70 which adds up to using more gas over several hills. Cruise control is rarely a good choice when going for mpg.

    Besides with an mpg of 41.96 you only lost 8.79% mpg from estimated. Remember, the prius c gets 46 on the highway.

    If you were in an SUV that gets 30 mpg and you get an average of 27 you may not think it's that bad but it would be worse than what you achieved since it translates to a drop of 10% mpg.

    Your biggest enemy is the cold though. No way around it.

    Don't worry about it
     
    #6 sisharp, Nov 13, 2013
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  7. ztanos

    ztanos All-around Geek!

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    That indicates they adjusted your pressure. I'm "assuming" you normally run your tp higher than manufacturers suggested rate. That will hurt you a little. If they dropped it lower than 30 that will hurt you significantly.
     
    #7 ztanos, Nov 13, 2013
  8. ztanos

    ztanos All-around Geek!

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    65-70 degrees isn't enough to drop it to the low 40s...
     
    #8 ztanos, Nov 13, 2013
  9. sisharp

    sisharp Member

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    In Cincinnati it's gotten to the low 40's in the past 2 weeks and even lower recently. The temp set in the climate control doesn't affect it but the outside temperature does.

    Also, last friday it was particularly cold throughout the day in chicago. Which is what his location says. Last friday began below 40 and maxxed out to around 45 degrees.

    This plus the winter fuel blend doesn't make for the best driving conditions.
     
    #9 sisharp, Nov 13, 2013
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  10. ztanos

    ztanos All-around Geek!

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    I read his thermostat temp as his outside air. Sorry.
     
    #10 ztanos, Nov 13, 2013
  11. Fahfoofnik

    Fahfoofnik Member

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    Ok, so sounds like nothing to worry about. That's fine. It just concerned me, as I thought I'd done everything right (didn't block the vent, had the car checked by the dealer before hitting the road, etc.).

    Was just shocking to see a tank of fuel go from 52-56MPG all the way down to 42-44MPG.
     
    #11 Fahfoofnik, Nov 13, 2013
  12. Fahfoofnik

    Fahfoofnik Member

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    No, to be honest, I've never adjusted the tire pressure higher than what the sidewall/owners' manual said. I have read several threads here about how "over-inflating" helps with achieving higher MPG, but I'm too scared to do it.
     
    #12 Fahfoofnik, Nov 13, 2013
  13. ztanos

    ztanos All-around Geek!

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    Which is it? Sidewall is much higher than what the owners manual says.
     
    #13 ztanos, Nov 13, 2013
  14. Hodr

    Hodr Junior Member

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    my dealer set the pressure at 50 psi, but it seems to be fine.

    Nexus 7 ?
     
    #14 Hodr, Nov 13, 2013
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  15. Deleted member 111882

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    Yikes...the highest I've had mine is 44 psi, and I could tell it was high because it was on a freak weekend with 70 degrees and electric braking on a straight road wasn't enough, my car just kept on going straight.

    On the hottest summer day, I had the A/C up to half and it was 97 degrees and still topped off at 53 mpg. So, I would not be happy with 41 mpg. My first guess is low tire pressure, but it sounds like something else is going on. So to ask Fahfoofnik: Did you have your oil changed at the dealer as well? How high up did they fill the oil? I've heard that too much oil hurts fuel economy. How much of your road trip driving was into the wind?
     
    #15 Deleted member 111882, Nov 13, 2013
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  16. ztanos

    ztanos All-around Geek!

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    It was the cold weather. Most assuredly.
     
    #16 ztanos, Nov 13, 2013
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  17. orenji

    orenji Senior Member

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    With all that weight in the car, you should be happy, what did you expect to get 60 MPG?
    This car with driver only gets me 55 to 60 MPG, on highway. Add a 2nd person and I can get high 40's on the highway.
     
    #17 orenji, Nov 13, 2013
  18. Mendel Leisk

    Mendel Leisk Senior Member

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    I think it's mostly the speed that's hurting your mileage. Things you can do:

    1. Stay to the right and under the limit.
    2. Choose secondary, lower speed highways.
    3. Drive with load, ie: let your speed fall off on short upgrades, recoup it on the far side.
    4. Drive strategically, keep a good buffer ahead (don't sweat it if someone "takes" the space), coast up to slow downs.
    5. Raise those tire pressures, moderately at first.
     
    #18 Mendel Leisk, Nov 13, 2013
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  19. Fahfoofnik

    Fahfoofnik Member

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    Owner's Manual is what I've gone by, sorry…should've clarified.
     
    #19 Fahfoofnik, Nov 14, 2013
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  20. Fahfoofnik

    Fahfoofnik Member

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    No, like I said in the original post, I wasn't expecting some astronomical MPG with the 2 extra people + luggage in colder weather. The drop off from 54-56MPG per tank to 41-44MPG just seemed really steep to me. I'm learning now that this drop off is considered normal.
     
    #20 Fahfoofnik, Nov 14, 2013
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