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Brand new Prius Owner, trying to figure out driving habits / path choice.

Discussion in 'Gen 3 Prius Fuel Economy' started by quickdrawgc, Jan 18, 2012.

  1. quickdrawgc

    quickdrawgc New Member

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    So I've read through some of the forums looking for informed opinions on correct ways to maximize mpg though proper acceleration and watching speed etc.

    I've got a fairly long commute (60 miles each way), of which about 60% of it I have only one path option. The other part I've got 2 path options.

    So maybe you guys can help me make an informed decision. (I know after a few weeks of testing I could probably figure it out experimentally, but would like to avoid that if possible).

    Route 1: 5.8 miles @ average speed 70mph (interstate, low traffic, virtually no stopping / breaking) + 17.2 miles @ average speed 50 mph on US 1 w/multiple lights 2-3 of miles apart.

    This route is 23 miles, adds about 8-10 minutes to the overall commute.

    Route 2: 17.7 miles @ average speed 70 mph (interstate, same as above but I take it farther), + 6.8 miles @ average 40mph (includes about the same amount of lights at closer intervals, a lot more stopping / starting including a quarter mile school zone)

    Route 2 is 24.5 (1.5 miles longer), shaves 8-10 minutes off the trip.

    I was thinking Route 2 is the best, even though I originally was thinking Route 1 was the best (due to longer stretch of 'city' driving speed). The 10 minutes time is a nice consideration, but I'm willing to get up slightly earlier to save money in gas.

    From my basic understanding of the gauges in the car (yay more bars on mpg list = better) I seem to get better instant mpg going on the longer 50 mph stretch, but I'm not sure if its canceled out by the large number of stops paired with need to accelerate back up to 50 mph (in an area that everyone gets mad and honks / swerves if you do it slowly).

    From you experienced drivers, do you seem to get better mpg out of 70 mph where you can set the cruise and only accelerate / break to get on the road and then off at the exit, or is it worth the stops / starts to do most of the driving at 50 mph?
     
    #1 quickdrawgc, Jan 18, 2012
  2. qbee42

    qbee42 My other car is a boat

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    Most likely route 1 will yield better mileage, due to the lower average speed. However, the traffic lights will have a strong influence. I am basing my guess on your statement that you have an equal number of lights both ways.

    Tom
     
    #2 qbee42, Jan 18, 2012
  3. quickdrawgc

    quickdrawgc New Member

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    The number of lights are similar, but in route 1 I have to get up to 50/55mph, route 2 its only 35-40.

    I may just have to chart it out over a few weeks. I haven't seen enough evidence either way that having to accelerate to 50 multiple is better / worse than traveling at 70 mph.
     
    #3 quickdrawgc, Jan 18, 2012
  4. jdcollins5

    jdcollins5 Senior Member

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    I have a similar commute as yours. My route is similar to your Route 1. I get better mpg on the highway versus the stop/start driving. To me, the longer you can stay on the highway and avoid the start/stops the better the mpg you will see.
     
    #4 jdcollins5, Jan 18, 2012
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  5. ksstathead

    ksstathead Active Member

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    Whichever route, try 67 or 68 instead of 70 on interstate sections.

    My gut is also longer interstate section = better mpg.

    Suggest you use trip B to test fuel consumed (not mpg), since we put fuel in the tank, not "mpg." My 1.5 mile commute gives horrible (~40's :p) mpg, but I'm not going to circle the city even though I could achieve 70 mpg.
     
    #5 ksstathead, Jan 18, 2012
  6. fuzzy1

    fuzzy1 Senior Member

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    I'm voting with qbee, for much the same reasons: Choice #1 has a lower average speed, and has the same number of lights. Plus it is 1.5 miles shorter, and total fuel is more important than mpg score.

    But there is much other detail missing that must be determined by actually running these routes. My own commute offers four different basic routes with numerous variations. Each presents different speed / topography / traffic congestion patterns that strongly influence hypermiling opportunities and overall fuel consumption, and they cannot be condensed into a simple description.

    My simplistic rules of thumb suggest that #1 will burn 0.077 gallon less than #2. That is about $0.25 at today's fuel prices, and the shorter distance is worth about $0.35 more in reduced depreciation (if you amortize by the mile, as I do) and maintenance. So that 8 minutes extra commute is saving you a bit over $4 / hour, less than minimum wage. But if you are reading PriusChat, your time has zero value anyway, so the savings may be worthwhile.

    I am not counting the extra energy required to get the car up to 50 mph after traffic lights, compared to 40, but this is likely to be swamped by traffic differences. And the 40 mph section could offer even more savings from engine-off glide opportunity not available at 50, but this will be very hard pressed to make up enough fuel to compensate for the extra dozen miles at 70 mph.

    The real answer requires real world test data to compare.
     
    #6 fuzzy1, Jan 18, 2012
    1 person likes this.
  7. quickdrawgc

    quickdrawgc New Member

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    Thanks for the input.

    I live in Florida, so the landscape is pretty much, flat, flat and more flat with a side of rare 'hills' that climb maybe inches? the largest inclines are the interstate exits or the bridges over them.

    The longer city route with the higher speed limits has more time spent moving, less stopped. The shorter city route is the main path off I95 down here and is very congested + the lights are very close together.

    You guys are right , I'm in the wrong mindset of mpg over the whole trip as opposed to fuel consumed over the routes I'm considering.

    As soon as I figure out the trip controls I'll get a test started and get some numbers.

    Thanks!
     
    #7 quickdrawgc, Jan 18, 2012
  8. car compulsive

    car compulsive Active Member

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    LOL Your thread title reminded me of my old Corvetteforum days when a new owner would always have multiple members advising them to "Drive it like you stole it".
     
    #8 car compulsive, Jan 18, 2012
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