Real World Range Questions (Winter)

[dsm363]

The reason slowing down gets brought up is that some people are hoping to take a "300-mile" nominal-range car on a trip close to 300 miles without charging. That's not the right kind of trip for the car. It's like buying a gas car with an advertised 30mpg and a 10-gallon gas tank on a 300-mile trip without refueling. Sure, it can be done...but there are so many factors that affect mpg, would you really try? If there are no gas stations along the route (or you just don't want to use them), then my claim is that is not the right car for the trip. Just like a Miata is not the right car to take the kids on vacation; it doesn't have enough seats. That doesn't make it a bad car; just the wrong car for that trip. Buy a different car (or at least have another one available; that's what most Miata drivers do) if you need to go near the edge of its range quickly without stopping in any weather.

(To complicate things slightly: I'm addressing people thinking about buying a car, and considering their driving. If you will regularly stretch the range, the car is not for you. Seriously, don't buy it; there are plenty of people that won't regularly stretch the range that will be happier with it. Of course, for those of you that do buy the car, even if you have a gas car available for a long trip, you won't want to take it. So then you might find yourself plotting how to make it work for a range-stretching trip. But that's not something you have to do, it's something you want to do. It will be easier to do once you've had the car and have a better feel for its capabilities under your own driving, terrain and weather conditions).

This is really excellent advice. I agree that if you're going to stretch the range of the car (250 miles non-stop at 65 mph with AC on as your goal) then the Model S might not be the car for you. It's also true that once you get the Model S, you'll try very, very hard to find a reason why you have to take your gas car on a trip and might be willing to compromise a little with slowing down or taking an hour break that you're not used to doing on a trip.

 

[Kipernicus]

even if you have a gas car available for a long trip, you won't want to take it. So then you might find yourself plotting how to make it work for a range-stretching trip. But that's not something you have to do, it's something you want to do. It will be far easier to plan once you've had the car for a while and have a better feel for its capabilities under your own driving, terrain and weather conditions).

You have described my feelings exactly. I know I'll want to drive the Model S on road trips because of its power, space, tech features, no gas, everything. But I do share the OP's concerns about the real world range being less than I hoped, and degradation being more than I fear. At the same time I also believe in your last sentence, that once we've had the car for a while we'll know how to plan a trip without inducing anxiety of any sort for the wife and kids.

 

[strider]

I think the range is right around where people were expecting it to be from the range vs. speed graph Tesla released previously. Tesla probably shouldn't have pushed the 300 miles at 55 mph range because while that's possible, it's unlikely to be something most people due since highway speeds are normally 65 mph and people tend to use their AC or heat.

But that's how their competitors were advertising (100 mile range in a Leaf?) and also that was how the EPA was rating back in the 2-cycle days. So it's a legacy thing and will take a while to shake out. The Leaf's 5-cycle is 73 miles but they still advertise it as "100*". It's the same w/ ICE vehicles - before the 5-cycle tests the mpg ratings were a joke.

 

[dsm363]

But that's how their competitors were advertising (100 mile range in a Leaf?) and also that was how the EPA was rating back in the 2-cycle days. So it's a legacy thing and will take a while to shake out. The Leaf's 5-cycle is 73 miles but they still advertise it as "100*". It's the same w/ ICE vehicles - before the 5-cycle tests the mpg ratings were a joke.

Tesla should definitely consider advertising the EPA rating even though their 300 mile range is possible to obtain.

 

[Citizen-T]

Tesla should definitely consider advertising the EPA rating even though their 300 mile range is possible to obtain.

That's hard to do when all your competition uses a different metric. Just ask the hard drive manufacturers.

I can think of dozens of examples like this. How about ISPs? You want to be the only ISP that advertises real world speeds?

That's a good way to go out of business.

 

[dsm363]

That's hard to do when all your competition uses a different metric. Just ask the hard drive manufacturers.

I can think of dozens of examples like this. How about ISPs? You want to be the only ISP that advertises real world speeds?

That's a good way to go out of business.

Good point. Tesla might also win points for being more honest too though. A few people have stated they feel mislead or even lied to about the range when Tesla advertised 300 miles then added 'at 55mph' saying that's not realistic. It's a judgment call on Tesla's part on what would do more harm at this point. They currently have no competitor in that range segment but will in the future.

 

[NigelM]

A few people have stated they feel mislead or even lied to about the range when Tesla advertised 300 miles then added 'at 55mph' saying that's not realistic. It's a judgment call on Tesla's part on what would do more harm at this point. They currently have no competitor in that range segment but will in the future.

In fairness to Tesla, I think we all see mpg averages advertised by other automakers and we don't suddenly turn around and expect to get that mileage when we drive 85mph on the Interstate. Because Model S is electric we're all (me included!) suddenly into the minutiae of exactly how many freeway miles we can achieve off a single charge.

 

[mknox]

Would a paid option be allowed (something like the Chargepoint network) where the utility could simply charge the cost of electricity with no profit?

We are a municipally-owned public utility and that is part of the problem, however, other utilities in the jurisdiction have installed charge stations. One I am aware of does use ChargePoint technology (requires a card) but does not charge for the power.

 

[smorgasbord]

In fairness to Tesla, I think we all see mpg averages advertised by other automakers ...

That's an official "EPA" number, which releases the manufacturers from real world expectations.

Tesla should just advertise the Model S 85 as an "EPA Range of 265 miles" and be done with it.

 

[NigelM]

That's an official "EPA" number, which releases the manufacturers from real world expectations.

Tesla should just advertise the Model S 85 as an "EPA Range of 265 miles" and be done with it.

The point I was trying to make is that we're all taking the EPA figures as an absolute for Tesla, but not for other cars. For example, I know that on my Roadster I get way more than my ideal range ever tells me when I'm driving constantly in town and therefore using regen all the time. In the end it comes down to driving style and conditions.

 

[dsm363]

In fairness to Tesla, I think we all see mpg averages advertised by other automakers and we don't suddenly turn around and expect to get that mileage when we drive 85mph on the Interstate. Because Model S is electric we're all (me included!) suddenly into the minutiae of exactly how many freeway miles we can achieve off a single charge.

That's the key difference. People treat EVs very differently in terms of EPA numbers because you can't simply fill up (easily) in minutes if your car is off 10-20% because of the way you drive.

 

[mknox]

In fairness to Tesla, I think we all see mpg averages advertised by other automakers and we don't suddenly turn around and expect to get that mileage when we drive 85mph on the Interstate. Because Model S is electric we're all (me included!) suddenly into the minutiae of exactly how many freeway miles we can achieve off a single charge.

One thing I've learned from this thread is that EV range is extremely variable based on conditions and driving. To the point above, advertised MPG does indeed vary, but it seems not nearly as much as EV mileage varies.

I've kept detailed fuel/mileage logs for years and even things like trailer towing may only reduce my mileage by 2 or 3 MPG which translates to 10 or 15 miles of range out of 300+ miles. Headwinds, HVAC use and the like are below measurable limits with an ICE car (based on my experience). My winter tires and cold weather reduce my mileage by almost exactly 1 MPG, but other than these things my range is pretty constant and predictable.

All good stuff to keep in mind.

 

[jerry33]

What do you guys think have a bigger effect on range? Running the AC or cracking some windows?

Well, we won't really know until someone measures it because the a/c is different and we don't know how much drag the windows and/or pano roof have. In the Prius a/c is a bigger hit than having the windows open a couple of inches, (A/C takes about four mpg depending upon how hot the day is and what you've set it at).

 

[NuclearPowered]

Well, we won't really know until someone measures it because the a/c is different and we don't know how much drag the windows and/or pano roof have. In the Prius a/c is a bigger hit than having the windows open a couple of inches, (A/C takes about four mpg depending upon how hot the day is and what you've set it at).

That depends on the speed of course.

Contrary to Mknox, I find that headwinds make a hell of a difference in MPG. I go from 46-47 or so to 39-40 in my Prius when facing a moderate headwind on the Interstate. Priuschatters have shown sidewinds to be comparably terrible.

 

[jerry33]

That depends on the speed of course.

Contrary to Mknox, I find that headwinds make a hell of a difference in MPG. I go from 46-47 or so to 39-40 in my Prius when facing a moderate headwind on the Interstate. Priuschatters have shown sidewinds to be comparably terrible.

There is a Vehicle Energy Use Simulator in the App Store. You can plug in all kinds of parameters about the car, tires, environment, etc. and get very accurate numbers.

And yes, headwinds make a real difference. I went from 70 mpg to 50 mpg on the homeward leg from Arizona when I hit some 25 mph headwinds at the tail end of the journey.

 

[MikeK]

One thing I've learned from this thread is that EV range is extremely variable based on conditions and driving. To the point above, advertised MPG does indeed vary, but it seems not nearly as much as EV mileage varies.

Be really really careful with your analysis here. MPG and range are related figures, but the relationship is highly dependent upon the efficiency of the vehicle. In an inefficient vehicle, a large change in range can accompany a small-sounding difference in MPG.

Let me elaborate.

You said that you lose only 2 or 3 MPG while towing a trailer. 3 MPG sounds small, but is it? You didn't say what the nominal efficiency of your car is (in MPG) without the trailer. If your car starts at 100MPG, then 3 MPG is insignificant, at 3%. If your car starts at 15 MPG, then 3 MPG is a whopping 20% change due to towing the trailer!

Gasoline contains approximately 36.6kWh per US gallon. So, Elon's 85kWh Model S ideally contained the energy equivalent of 2.3 gallons of gas, and with it, they drove 230-odd miles, for ~100 MPGe.

Accounting for unused energy in the pack and remaining range displayed, Motor Trend figures they fell 11% short of the EPA range figure. In a 100+ MPGe vehicle, an 11% drop in efficiency sounds big. "Wow, it lost 11 MPGe just due to a lousy headwind and some hills!"

But in a 22 MPG ICE, 11% is "only" 2 MPG.

So, I'm going to suggest that generally speaking, your range has probably varied substantially over time, even though your MPG doesn't sound like it has, because your vehicle is substantially less efficient than the Model S.

I think many people are not very conscious of the range difference they achieve during their day to day driving. First of all, if you're doing commute-type driving, winds probably average out during the course of a tank's worth of gas. And, since fuel gauges are notoriously inaccurate, most people fill up when the needle gets "sort of low". They don't get the precise readout that an EV provides, and they just plain don't pay that much attention.

Another factor at play here is the nature of Motor Trend's test: they took a road trip. Road trips can be different from daily driving. If you happen to have a prevailing headwind on a road trip, then that headwind is working against you for the whole trip, and there's no chance for things to average out. In an ICE on a road trip, you could see a substantial decrease in distance between your fuel stops with a prevailing headwind. Or, a tailwind could stretch your distances. But, unless you do that same trip all the time, how would you notice?

Certainly, when my friends and I drive to Tahoe, we notice that we use a lot of gas getting there, and a lot less getting home. Why? Because there's a net elevation change of 6000 feet or so, and it works against you one way, and with you the other!

I'm a pilot, and if there's anything pilots pay attention to, it's wind. Small airplanes are a lot like EVs, actually. You really have to plan your trips, because you carry a relatively small amount of energy onboard, compared to the distance you need to travel, and fueling stations are time consuming and somewhat scarce. You might choose a different en route altitude because at 6000 feet you have a 10 knot headwind, while at 8000 you have a 3 knot tailwind. You'll get there faster and burn less gas at 8000 feet.

The Model S has enough range that for daily driving, it's pretty much in the territory of "don't even think about it". With a longer trip, because charging is slower than refueling with gasoline, and the locations are not as plentiful, it's more like flying a small plane: a little planning goes a long way.

 

[William13]

I predict that having the windows open instead of using the A/C was less efficient in the Model S due to the drag of open windows. Jerry33 (a hypermiler) only opens his Prius windows a few inches. I and most other people would open the windows more widely. The article doesn't specify.

 

[Doug_G]

Driving a Roadster, I've found the biggest environmental impact on range is temperature. It's not just thicker air, either - the rolling resistance of the tires goes downhill too.

Running on snow tires or standard street tires you'll see about a 10% loss of range at freezing temperatures. If however you are running sticky tires it can be quite a bit worse. I had an unexpected surprise this spring when I went to a performance driving school in another city. I had put on the A048's for the school, and then when I went to leave the temperature had unexpectedly dropped to near-freezing. My range went absolutely into the toilet, with range as much as 20% to 25% worse than normal. This didn't cause me range anxiety, but it did result in some schedule anxiety because I had to really slow down and spend more time charging.

Seat heaters have a pretty much undetectable effect on range. Cabin heat could be 5% to 10% depending on the situation. Air conditioning in my experience has a small impact.

And yes, headwinds do matter. I've noticed my eastbound trips have a little more range than my westbound trips, probably because of the prevailing winds.

 

[brianman]

the rolling resistance of the tires goes downhill too.

Does that mean they perform better or worse? Metaphor context confuses me here.

 

[mnx]

Does that mean they perform better or worse? Metaphor context confuses me here.

Really? I think it's rather obvious from context that the rolling resistance went up.

"My range went absolutely into the toilet, with range as much as 20% to 25% worse than normal."