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Interstate vs, State Hwy. 100 mile trip

Discussion in 'Prius v Main Forum' started by David Prius V, Apr 28, 2012.

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  1. David Prius V

    David Prius V New Member

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    Interstate vs. State Hwy. 100 mile trip

    We have a 100 mile trip (each way) we make every month or so to pick up or drop off our son at UF, I have read that the "sweet spot" for highway travel is 71 mph in the V (?). As an alternative to the interstate route, I could take the state highway system which is more scenic, but adds about 25 minutes each way, and includes a number of red lights with a mostly 65 mph speed limit. My question is will my gas mileage be better taking the road less traveled? Or, is a constant cruise at 71mph my best bet. I really don't mind the extra travel time.
    Thanks in advance.
  2. Wanderer

    Wanderer Hybrid neophyte

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    In my experience the slower you go the better your gas mileage gets. (assuming all other factors equal). I suspect taking the road less traveled will improve things but only you can decide if a few mpg is worth the extra time. I think the sweet spot is a little lower. I'd say more 55-62 but that may impede traffic depending on location. We have mostly 60mph speed limits around here so that is reasonable for my area. W
    1 person likes this.
  3. CLUBGUY

    CLUBGUY Member

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    Re: Interstate vs. State Hwy. 100 mile trip

    I really don't mind the extra travel time.

    The question is "how much fuel is being used" during that "extra twenty five minutes"..??
    Total "DIFFERENCE" in fuel used is the question...!!
  4. btcompute

    btcompute Junior Member

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    Re: Interstate vs. State Hwy. 100 mile trip




    It seems to me the only way to know the answer is to try both routes and see what happens.
    Compare the difference in cost of fuel to the extra time that the slower route will take, then decide what works best for you.
    tanasit likes this.
  5. David Prius V

    David Prius V New Member

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    Thanks. I've only had the car for a week. I thought the 71mph "sweet spot" seemed too fast. I guess there's a reason the hwy EPA estimate is lower.
  6. catgic

    catgic Master & Commander Hybrid Guru

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    David Prius V – The 71 MPH is a Rule-Of-Thumb “Sweet Spot†speed point, where fuel burn efficiency against the power curve of the 1.8-Liter engine is “Sweet.†Of course, if you went slower (lower RPM), like the 55-62 MPH Wanderer suggests, you would use less fuel. Conversely, going faster (higher RPM) would burn more fuel to achieve an increased power point higher up on the Power Curve. The 71 MPH “Sweet Spot†Rule-Of-Thumb is for use by drivers using only Prius v OEM instrumentation (i.e. no ScanGuage, Tachometer, etc) to pick a good cruise-travel speed for Interstate/Open Highway travel.

    Knowing this nominal “71 MPH Sweet Spot,†particularly in the State of Florida where the Max Legal Highway Speed is 70 MPH, gives fuel consumption conscious drivers some useful knowledge. It lets them know that traveling at a speed above the “71 MPH Sweet Spot†will cause them not only to burn more fuel per incremental additional MPH, but to burn it more inefficiently, from an added power point of view --- while chancing receiving a costly speeding citation.

    I am a long time resident of Florida who knows the Interstate and Off-Interstate alternative Tampa-To-Gainesville route(s) you are pondering. I do not think driving on the back roads alternates are worth increased Per Tank-Full MPG fuel economy you might gain weighed against added Point “A†To Point “B†trip time. If I were making the drive, I would take I-75 and travel at a Cruise Control Set Speed of 65-66 MPH. This would deliver you the best balance of MPG Fuel Economy vs Trip Time.

    I regularly travel up I-95 from the Space Coast to JAX, which is ~170-miles. If I am not in a hurry, I cruise along with the ECC set at 66 MPH. If I am in a hurry, I set the ECC at 71 MPH. The 5 MPH difference is worth about 12-15 minutes. Running with the ECC cruise set at 66 MPH (~47 MPG, Measured Per Refill Method) gains me about 2MPG on a Per Tank-Full Top-Off On Arrival basis, as compared to cruising at 71 MPH (~45 MPG, Measured Per Refill Method). At today’s gas prices, 2 MPG over 170-miles is worth about 75¢ worth of Unleaded Regular Gas, or a $1.50, for the round trip. :plane:
    tanasit and David Prius V like this.
  7. David Prius V

    David Prius V New Member

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    Great answer and information. Thanks very much.
  8. cdltpx

    cdltpx Junior Member

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    I am a former trucker I would advocate taking the shorter interstate route but with a twist. Rather than do 70 you find a truck that is governed (neutered) to 62-65 mph and tag along with him try not to tag behind tank trucks did that one time he leaked chemical on my car and ate some parts off. Just remember when you drive you have to count a second following distance for ever 10 mph you drive. If MPG is suffering you know you are in the wrong spot there is a sweet-spot where he will break wind for you and you will be far enough back not to affect his ride quality. If there is a Prius behind my truck I knew it my front end would bounce left to right because the car behind me affected the air flow.
    When you drive 62 you are not driving you are more a steering wheel holder the other faster pussycats will blow past you with their ulcer causing habits. I have avoided so many incidents by A. keeping proper distance and B. just doing 62 or 65 behind a neutered truck.
    They call the fast lane the hammer lane since truckers use to say they put the hammer down on the accelerator to go fastest hence hammer lane.
    I feel they should call the slower lane the neutered lane since that is where the economical drivers or company drivers with neutered trucks usually stay.
    How Much Is Your Time Worth? Thoughts on Speeding - The Simple Dollar
  9. testuserER

    testuserER Guest



    He quoted the difference in TIME, not mileage. The mileage difference might not be much at all.

    From a quality of life standpoint, I like the less travelled roads.
    On a motorcycle I find Interstates with heavy traffic stressful.
    And if you stop at places that look interesting, you often meet some really nice people.

    Those that roughly parallel an Interstate often have little traffic AND little damage due to the lack of trucks.
  10. JimboPalmer

    JimboPalmer Nadir of Wrongness

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    I get 5 MPG more at 61, even with stop signs and passing, than I do at 71 on the freeway.
  11. vvillovv

    vvillovv Member

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    there is no hard and fast rule to apply to any two unique different routes or two drivers of any specific route.
    You just have to drive them both yourself and see which one you like better, then tell us about your experiences sothey can be added to the prius experiences database..
  12. rjparker

    rjparker Active Member

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    For absolute cost savings the lower speed route seems logical. However that's true only if the distances are the same and sometimes interstates have longer routes; sometimes state highways have longer routes. Forcing a route via Google Maps may tell you which is shortest.
  13. SageBrush

    SageBrush Senior Member

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    Hogwash.

    Drive 65 mph and you will get low 50s MPG. The extra 25 miles each way is some 25% more fuel. You cannot hope to recoup that, even on a more fuel efficient route.
  14. rjparker

    rjparker Active Member

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    The Original Post said 25 minutes extra not 25 miles...
    SageBrush likes this.
  15. vvillovv

    vvillovv Member

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    Sorry, the reason I posted above without diclaimer(s) is that I personally have found that incline has substantial effect on mileage.
    I've become hopelessly bias with that regard it appears.
    Obviously " substantial" is relative to the individual.
    Last edited: Aug 3, 2014
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