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Model S mileage in City vs. Highway

Discussion in 'Model S: Battery & Charging' started by Keith Gilabert, Aug 6, 2014.

  1. Keith Gilabert

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    Is the Model S more efficient in the City or Highway?

    Also, If I stay overnight will the charge continue to dissipate, thus giving me lower mileage expectations the next day?

    Thanks,

    Keith Gilabert
     
  2. Chipper

    Chipper Active Member

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    I think it is equally efficient---depending on how you drive it. The nice thing is you have a constant readout available on-screen if you'd like, that gives you your current usage. You can also look at the graph over the last 5/10/30 miles.
     
  3. AndyM

    AndyM Member

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    Chipper is right - it depends how you drive it.
    However, it is much EASIER to be efficient using cruise control on the highway.
    I typically drive my 21" wheel Model S at 68 mph, and when there's no headwind, my watt hours per mile is close to rated range.
    In the city, with stops and starts, it is higher. This is exactly what you get with any transportation method: an object in motion tends to stay in motion, and uses less energy to move... you're still using energy to plow through the air.

    Your second question on charge dissipating: Model S is really good at not using its battery overnight. In temperate conditions, and using "sleep" mode in the car, I've noticed only maybe one mile draining away during the night. In moderate winters (around freezing, in Oregon), before sleep mode was enabled, I'd lose 10 rated miles in the parking lot at work during the day. Tesla has fixed that now. You can expect to lose very little overnight. Tesla's advice is still the best - plug in when not driving if you can. If you can't - and if you have enough to drive the next day - just don't worry about it.
     
  4. DuncanWatson

    DuncanWatson Member

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    For most electric cars city driving is more efficient since the stop/start penalty is much less than the speeding over 60 mph penalty to efficiency. This is the opposite of ICE vehicles and why highway mpg for an ICE is better than city mpg.
     
  5. Brass Guy

    Brass Guy Member

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    Efficiency still depends on several factors. The optimum speed is something like 17 mph, only if it is constant though. Stop-and-go is very inefficient, as is driving 80mph. I've found that driving rural roads with a small amount of stop-and-go, probably averaging 30-35mph, is more efficient than even 60mph highway. (In both cases I beat the rated range estimates.)

    So it depends on what "city driving" means to you. If your in Boston, NYC, LA or SF, you're probably stopping a lot so less efficient. If by "city" you mean anything that's not a limited access highway, then it could be more efficient than driving highway speeds.

    As for overnight losses, AndyM hit it right on. MS has a "energy saving" (sleep allowed) mode that can be turned off. If it is off, you will loose several miles overnight, but with it turned on you may have to wait 5-10 seconds to drive from when you unlock or open a door.
     
  6. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    I've found there's not a lot of difference between city and highway, but the nudge goes to the city. Terrain, driving style, and traffic patterns tend to make the difference of whether one is better than the other.

    Yes, it will lose some range overnight--even when sleep mode is on. Most of us look for places to stay that we can plug in. Even a lowly 110 will keep the range up and may even increase it a bit. You might want to check out the additional adapters in the Tesla store.
     
  7. trils0n

    trils0n 2013 P85

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    For me city driving is much easier to get low energy consumption. I'm usually in the range of 270-280Wh/mile in city, and 320+ on the highway. I get the best numbers (sub 260Wh/mile) on roads with speed limits in the 30-50mph range, with few stop signs/lights.
     
  8. tdiggity

    tdiggity Member

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    I get much better power usage on the freeway. Lots of stop and go for me in the city.
     
  9. PhilBa

    PhilBa Active Member

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    I think the efficiency break is between short and long trips. Short trips for me are always less efficient, especially if there are any hills involved. The grocery store is about 3 miles away with about 300 ft of gain and loss round trip. I get 340-350 wh/mi in summer. Another drive I do regularly that is about 12 miles with about double the gain/loss and I get 320-330 in summer. Both drives have about the same speed limits.
     
  10. William13

    William13 Member

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    PhilBa mirrors my experience. City driving can be more efficient depending on driving style. Maximal efficiency is achieved at 30-45 mph. When it is cold outside the efficiency goes way down when making short trips. This allows time for the battery to cool off each time.

    I must say that even in good weather my city driving efficiency is much lower due to my quick off the line starts. I average better efficiency at highway speeds until I hit over 80 mph.
     
  11. David_Cary

    David_Cary Member

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    Isn't the concept of city/highway a little too simplistic.

    Also city is about how you drive it. You should be able to get way better efficiency in the city if you try. Since most people can't, they are pretty close.

    City to me is 35-45 mph with a stop once a mile. Not everyone's idea of city for sure....
     
  12. donv

    donv Member

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    I seem to get better efficiency on highway trips than on my daily commute. However, my daily commute (all stop and go driving) involves a lot of hills, both up and down.
     
  13. gregincal

    gregincal Active Member

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    That sort of city driving makes for good efficiency. However what I call "town driving" (i.e. accelerate to 30mph, drive for 2 blocks, stop at a stop sign, repeat) makes for lousy efficiency. Luckily that also is generally for short trips, so it doesn't impact my overall average much.
     
  14. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Agreed. Short trips are always energy hogs.
     
  15. PoweredByRain

    PoweredByRain Member

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    There are far too many factors to be able to answer this simply. In my city, city driving is more efficient.

    The biggest factor in energy usage per unit distance is speed. At higher speeds this is mainly due to wind resistance. Driving 75 mph consumes a whole lot more than 65 mph, and a noticeable amount more than 70 mph.

    If you want efficient driving in the city, avoid using the brake pedal except for that final bit from about 5 mph to zero. If possible, avoid that as well simply by timing the deceleration well. Regenerative braking is surprisingly efficient.



    Yes. That's not a great feature. You can minimize the losses, however, by selecting "Display" and turning energy save mode on. The car will respond more slowly when you get in but the energy usage while the car is just parked will be much lower.

    - - - Updated - - -

    I'm curious how you know this. What losses are there in shorter trips which are amortized over a longer trip?

    I suspect the energy usage reported for a short trip includes the losses while the car was parked, which is why a short trip looks particularly bad.
     
  16. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    On a short trip, the tires and fluids in the reduction gear box never get to warm up. It's surprising how much extra energy cold lubricating fluids take. With the tires, they are at their most efficient when they have reached thermal equilibrium. There are likely other items as well, but those are the two biggies that happen all year round. In the winter there is also the battery and heater. Even if you pre-heat (or pre-cool in the summer), energy is still used (just not range). The shorter the trip, the fewer miles this gets amortized over.
     
  17. PhilBa

    PhilBa Active Member

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    Exactly. It's especially true when the temperature is less that 50 F and battery warming kicks in. You amortize that cost over more miles with a long trip. In warmer weather it's not quite as pronounced but I definitely see the short trip effect.
     
  18. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    A lot of how efficient "City" driving is depends on the city and the driver.

    If "city" driving is a lot of 30-50 mph driving with U.S. Midwest behavior, then it's easy to drive for a while between stops and then use mostly gentile, regen to come to a stop. This kind of driving is very efficient.

    If the driving is Paris or Tel Aviv style "city" driving, it is very different. This entails a lot of sitting stopped (very inefficient) driving with motion that is mostly a green-light max acceleration until you get to a red light or a traffic jam and then use almost full brakes wasting energy heating the brakes up. This kind of driving is very inefficient.

    Most cities are somewhere in-between. Is you city driving like you are in Des Moines or in Paris?
     
  19. caddieo

    caddieo Member

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    I haven't bothered to locate and track down the posting but didn't somebody in South Florida set a record of about 400+ miles? As I recall, there were no hills and the route was mostly rural and village roads with low speed limits that were adhered to or else driven under.
     

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