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Energy-efficient driving

I am currently experimenting with ways how to drive my Tesla as energy-efficiently as possible, and I have found a way where preliminary results show a 10% reduction in consumption.

Story: I currently have a loaner, provided by the fantastic Denmark Tesla team, when my 12-V Battery malfunctioned for the 3rd time in 3 weeks - they actually transported a loaner 400 miles to Stockholm and brought down my car for repair - WOW!!

This loaner, though, consumes about 10% more energy than my proper car with identical trips, identical settings and, as far as I can see, identical driving. Because of an imminent long haul this concerned me very much, so I started to think of ways of bringing down the consumption. I got the advice from a Tesla man: drive it as you would drive an ICE.

OK, fine. I have developed a style of driving with ICE:s that invariably beats their own consumption figures (and we all know that they are the "optimal" ones anyway). It is quite easy - roll the car in Neutral as much as circumstances allow.

I tried this with the loaner, and it immediately yielded really good results - minus 10%, from 310 Wh/mile to 278 Wh/mile in 40 degrees F.

The Tesla is built with such a small wind and rolling resistance so that these 2 factors coupled with the huge mass makes the Tesla roll "for ever", especially in a down-slope. If there's just a small decline it doesn't even lose speed.

The gearbox is so well-made that I learned in less than 2 minutes how to change back and forth between Drive and Neutral without anyone noticing anything.

So, if you free-roll and want to lose speed, put it in Drive and engage re-gen. If you want to keep the speed or increase it, just put it in Drive and - well, drive.

The Cruise Control doesn't do this well - it constantly gives small "puffs" of energy and then brakes, for instance when you reach a small hill, and the re-gen cannot be 100% efficient, so you lose more than you gain, whereas, if the hill is small enough, you just roll over it in Neutral or you see it coming and accellerate slightly BEFORE the hill and roll down after it (never accellerate uphill, if it can be avoided).

This car has such eminent rolling features that this can be done without at all disrupting the traffic flow, if applied intelligently (mostly meaning rolling downhill, but also anticipating a traffic jam or light).

I called Tesla and asked them if this could in any way, shape or form damage the car (I am driving a loaner, and I am much more careful with other people's properties than with my own), and the answer from the Danish SC was an unequivocal NO.

My lifetime average consumption (incl. the multiple showing-off accellerations in the beginning - I am only human...) with my proper car is 289 Wh/mile, with the temp has varied between 29 F and 50 F. Applying the free-roll system, I think I will get it down to 260 or thereabouts. Will keep you posted.

Would be interesting to hear, if anyone else has tried this and their experiences.

Robert

Very short answer (at least for me):

Oh dear. I missed that. Apologies to Tam!

I don't believe that foreigners appreciate being corrected in open Fora unless they ask for it. It is a touchy subject, to say the least. I have absolutely nothing against it for myself, since I believe in learning, but I have seen a lot of occasions, when the correctee simply withdrew to stop the embarrassment.

Humour is funny when directed against oneself or non-named others, almost never when someone else has to "foot the bill".

Given the service level and attitude of the Tesla Danes I really have no right to complain, except that I strongly suspect that the loaner has been restricted in some ways, esp. accelleration. I let my brother drive a short while, and of course he floored it. The result was nowhere near what I experienced in my car, but he dropped his jaw. Must check up on that.

Thanks for writing and again Sorry, Tam! - Robert

My mother was an English Professor and I spent my entire life being corrected. I'm quite used to it but I sure can see where somebody would find Brian H's corrections to be both pompous and unwarranted. There seems to be one on every forum I belong to, however, and Facebook also has its share of "grammar police" and "spelling police".

I take it with a grain of salt but then again English is my first language and I'm not very skilled at it much less any additional languages.

I do love my Model S and learn a lot from these forums.

At least on facebook you're being embarrassed by "friends".

@Robert - I am glad you are experimenting with your new gadget on wheels. Please do so without sacrificing your own safety while driving.

Personally speaking, I tried many hypermiling techniques with my hybrid. It was a self challenge at first but after a few years, all my techniques produced perhaps 10 - 15% extra efficiency. I grew tired of hypermiling in the hybrid after a year or so.

My S60 averages about 415 KW/h since ownership. It doesn't bother me one bit that I'm using about 30% more energy than most of the MS owners.

I drive the MS like the awesome toy that it is. My daily city commute is four hours long but only cover 50 miles. There aren't many opportunities for me to go over 60 mph for more than a few seconds.

I enjoy bolting between traffic lights since there are no other ways for me to create the obnoxious grin otherwise.

I would suggest driving the MS in such manners allow you enjoy the car. It doesn't matter if you set it to cruise control at speed limit or have jack rabbit accelerations at every intersection. The MS is a great ride regardless how you choose to drive it (within safety limitations, of course).

@Mathew98

Whatever works for you. I suppose it has to do with why one bought the car - as a beautiful toy or to "save the world".
As I also have said a number or times, we simply don't have charging stations in Sweden, which means that planning and economizing are mandatory, if you want to take the car to anything else but a commute.

I, having been one of the great bad energy-wasters previously, before my daughter (who, incidentally, is quite a bit smarter than I am) started to talk to me in earnest, have completely turned around (I am Robert, and I was an energy-waster. Hello, Robert, comes to mind), and am now investing heavily in trying to make up for past sins. I try to remind myself that, even if the Tesla is a great reduction in emissions, the electricity is generated from something, and that something may NOT be particularly good for the environment. I earnestly believe that we should take the necessary steps voluntarily, before we are going to be forced to (anyone remember the queues for gas in 1973? No?? Short memories).
So I try to save even with an energy-saving vehicle.

Robert

I tried "N" since yesterday and got better range! But that was just a minor point. The major finding for me was how much more fun I had by having more driving variables. Before MS, my cars were standard shifts. MS simplified it from 3-pedal + 1-stick driving to 1-pedal driving. Now I'm using the shift between N and D on top of the accelerator and break (most of the case I shift to D for break)...

Is it true that such shift is bad for the car? Someone wrote it with no supporting evidence. Does anyone have evidence?

Of course, safety is first. And chances are, I can be tired of it one day.

There is that little detail that coasting in Neutral in illegal in most, if not all States in the U.S. at least.

@Cindy123

I put that very question to the top technician in Tesla Denmark, and he confirmed that this is perfectly OK. Will not harm the car

But, to be double sure I asked Jerome Guillen, who is Vice president of WW sales, and he answered in the same vein.

I had another stint of 37 miles tonight in pitch dark, 50 degrees F and pouring rain. However I tried, I couldn't get it under 170 Wh/km or 272 Wh/mile, and I have noticed before that the consumption in rain is considerably higher. Probably has to do with rolling resistance, fan to get moisture away from the windshield, wipers going etc.

Robert

@shs

Are you totally sure? For how long? That would mean, theoretically, that you can't change gear with a stick shift car, since you are then coasting in Neutral (or having the clutch down, which is the same thing) while changing gears.

Interesting. This is the Swedish State Authorities' Homepage:
Så kör du sparsamt med automatlåda
(This is how you drive unwastingly with automatic transmmission)

Här hittar du fem tips på hur du kan köra sparsamt med automatlåda.

(Here you find 5 hints how to save gas with automatic gearbox)

.
.
.

5.Rulla mer
Automatlådan saknar motorbroms. När du släpper gasen rullar bilen långt. Med god framförhållning släpper du gasen tidigt och utnyttjar rörelseenergin för att spara bränsle.

(5. Free-roll (coast) more. The automatic gear lacks motor brake. When you lift the foot from the gas the car will roll far. With good planning you lift off the gas early and use the kinetic energy to save on fuel).

I find it really odd, if the State Authorities feel so differently about exactly the same thing. And, to be sure, I find the American Law totally incomprehensible, if indeed it is like you say.

Of course there is no legal difference between automatic gearbox and manual.

Robert

Robert,

From the CA DMV website. It applies specifically to down grades. I believe there are similar laws in most states.

V C Section 21710 Coasting Prohibited

Coasting Prohibited

21710. The driver of a motor vehicle when traveling on down grade upon any highway shall not coast with the gears of such vehicle in neutral.

How on earth could a law enforcement official determine that someone was driving in neutral? This seems highly unenforceable. What am I missing?

Also, a good attorney could poke a fair number of holes into that CA statute as it applies to an EV.

Robert,

When I was learning to drive many years ago in Michigan, I would often coast in Neutral, but then somebody told me it was illegal and dangerous, so I stopped. Years later I encountered this technique in a taxi in Beijing. As soon as the driver saw that he would need to stop for a light, the taxi went into neutral and the ignition, off. If a Chinese taxi driver uses the technique, there is no doubt something to it in terms of saving energy when you need to stop anyway for a traffic light or stop sign.

I also believe that people should drive in a manner that suits them. But I do have a few comments

1. regen does not use the brake at all. It is pure motor braking.

2. coasting on some hills may require some drivers to use the brakes to the point where they glaze and can no longer stop the car. This I believe is the motivation behind the no-coasting laws. Enforceable or not, the proof of the pudding is the presence of dead runs on mountain slopes in the Western US and mountainous regions of the east.

3. One question: when you coast Robert, do you attempt to keep your speed constant by braking or do you truly freewheel, no matter what speeds you attain?

@David Trushin

There is no fixed answer to that. Obviously every situation is new, and equally obviously I have to adjust my driving to the topography, traffic situation etc. If alone, I would let the car attain the speed it wants to, as that's the whole point of the exercise - to save energy. Whatever I gain helps me get further after the downhill.
I don't use my brakes basically at all. If I need to slow down when coasting, I choose Drive and lift my foot (well, I don't have to, since my foot anyway was on the brake pedal, but without braking). The incredible gearbox lets me do this totally smoothly.
I value my license, so I don't let the car exceed the given speed limits by more than the usual "VAT", unless I am in a situation where everyone else does so (I don't want to interrupt the traffic flow). Of course, if I am alone, well...
I drive in Sweden. We simply don't have roads with that steep gradients as you seemingly do, or the Swiss/Italians/Austrians do. I have driven lots in the Alps. To coast down there would be inviting someone to write my obituary, stat!

Again, any driving cannot follow fixed rules (except the State given ones, like normal traffic rules). One needs to apply some forethought, but I can assure you, that becomes second nature after a while. I have done it for decades, and I invariably beat the Manual-given consumptions. The Swedish State invites this way of driving, and I am perfecting it. The Tesla fantastic free-rolling properties makes this more of a pleasure than ever before, with any car. Why, when I change from Drive to Neutral, it actually feels that the car is accellerating for a split second, like it were tellng me that "back off, dud, I can do this better than you".

What a car!!!!

Robert

Oh, before the Language Police arrest me:

"I have driven a lot in the Alps".
"The Tesla fantastic free-rolling properties make..."

Why can't one edit the posts??

Robert

@shs

For mountainous roads, I can absolutely see the point in not coasting. But do they forbid just pressing the clutch while the car is in gear?
It is a stupid rule, since it is unenforceable. Any unenforceable law is stupid, since it takes away respect for the law in general. Better would had been a warning sign: Coasting downwards in steep gradients is DANGEROUS.

Robert

OK. So My commute is a mere 3.6 miles one-way. Going down to the office on my gentle downhill grade I've enjoyed experimenting with driving longer through slower neighborhood streets before getting on the local highway in an effort to minimize energy consumption. Even done the coasting thing. It's fun! Definitely a game. Though I have to confess, I feel conscious if I'm rolling along gently and an ICE car comes barreling down behind me hitting the brakes because of my slower speed. Don't want to give Tesla a bad name if you know what I mean. Anyway, on my best days, on my way to work, I've consumed about 260 Wh/mile. Of course driving back up the hill after work, I consume quite a bit more so that my round trip averages about 300 Wh/mile on a good day. So my 7 mile round trip consumes about 2.1 kWh when I'm being good. Now where the cookie crumbles for me is that while the car sits in the office parking lot for the whole day (if I don't take her to lunch) she loses 7 rated miles of range or another 2.1kWh just playing with herself. So my actual commute consumption ends up being more like 600 wh/mile!!! Bottom line: drive more for better Wpm but drive less to save the planet. Oh and Elon pleeeeeease fix the vampire drain.

His, hers, its;
He's, she's, it's.
Infallible.

robert;
The extra step to "re-engage Drive" cannot be as quick as "live" control of the regen function with the foot, feathering the pedal to keep energy flow at 0. Not possible.

Test drives prove nothing; it would take thousands to statistically sample the relevant universe.

Joined Mensa in my late teens; found a few narrowly focussed egos, trying to display their feathers. Got bored and left. Haven't sampled other chapters, but see no evidence of any group contributions.

"Regen" is a unique-enough colloquialism to deserve a place in the list of acceptable key-stroke savers.

Do you honestly resent corrections in your non-native language? That takes brass ones.

Robert, are you sure that the Swedish webpage you quoted actually recommends coasting in Neutral? It just says to lift your foot from the gas pedal earlier. It doesn't say to shift into Neutral.

(I don't speak Swedish, so my comments are based on your translation.)

@ye.

Yes.

Robert

@ye

No. Will check.

Robert

@ Brian H.

I feather the gearchange lever in the same way as I feather the brake when coasting. I have at least as good reactions in my hand as in my foot (especially when I occasionally put the latter in my mouth), and the Tesla gearbox is incredibly fast, virtually instantaneous. Having said that, no system is better than the person implementing it, and it needs the driver to actually think about what he/she is doing, until it becomes second nature and is done with the "spine". It may well be that you are right in theory, and so I will not stretch the point. Also I think it is a very moot one.

Oh yes, test drives prove everything, or why do you think that car manufacturers send whole teams (half factories, it sometimes seems) to the North of Sweden in order to test their cars in winter conditions? Test driving under controlled circumstances actually points at problems and very often gives good hints on how to solve them. I try to do my tests in as controlled circumstances as possible (e.g. using the same run with different driving styles to collect data from) and then draw my conclusions, and I know both how to do so as the usual logical pits, into which one may fall when drawing one's conclusions. In any case I only want to prove a tendency, not exact percentages, and that I have done to my absolute satisfaction decades ago. The only question was if those principles also applied to Tesla driving, and, to my satisfaction, they do, and even more so than with an ICE. Then, being a generous soul, I wanted to share my findings with others, who may share my opinion about global energy waste, or simply have a need to get further than they are currently doing on a single charge. The others don't have to read, and, anyway, in the nicest possible way, sod them :-).

I do agree with you about Mensa, but I only said that I founded the Finnish chapter, not that I am an active member.

Regen. Yes, of course it is; my comment was only a (not very clever, I admit) attempt at a small dig at you. You don't leave all that many openings for attacks, even though your statement about test drives certainly is one.

Well, I am going to stick my neck out, since (as already stated) I am a generous person and I want to give you the chance to chop my head off, and state that I don't think that even you, barring sloppy typing, will have a lot of reasons to correct my usage of the English language. Or a number of others for that matter. I also like to add, again as already stated, that I welcome corrections to my language, since I believe in learning as much as possible. However, and having said that, I do know of several instances, when such corrections, whence-, how- and whyever they were made, have been perceived as ad hominem attacks by the correctee, and therefore led to a silencing of same. I personally don't feel that a Forum about the Tesla cars is the right place to disseminate linguistic tuition, especially not, when it is as unasked as possibly called for.

I don't believe in false modesty. And yes, I do polish them daily.

I believe that, after now having made our positions clear, we are going to get on like a Tes.. oooops, house on fire.

Very best - Robert

@ye

Have now checked with the highest authorities in Sweden for traffic. Not only is it not forbidden, it comes highly recommended, using one's loaf, of course - not downhill a steep mountain. The reasoning was that they cannot micromanage every driver's possible mistakes - learning how to drive is part of getting one's driver's license. To outlaw something that good for the environment just because one or two idiots shouldn't have got a license in the first place is not on in my country.

"So, yes, by all means, put the car in neutral and try to use the kinetic energy already worked up." was the final recommendation in the telephone call I just ended.

Robert

Robert, thanks for the clarification. It now sounds to me like your process is one that essentially does manually what the car does automatically. As you said, you apply more intelligence to yhe process and you seem to get better results. I must admit, though it sounds like a lot of work for small returns. You are already saving the planet by not using gas. But saving 10% more is little compared to paving the way to the future of everybody leaving gasoline behind.

To outlaw something that good for the environment just because one or two idiots shouldn't have got a license in the first place is not on in my country.

It seems the USA is constantly mired in enacting laws that prohibit people from doing things simply because one or two idiots found a way to do them in such a way that property or life was endangered.

@David Trushin

I disagree. If I drive my Tesla 10% more efficiently it is like a fart in Universe, agreed, but the beauty of this is that this driving modus operandi is applicable to all cars. If even a tiny percentage in their Hummers and what-nots started to think what they're doing (noone more zealoty than a convert, right?) and saved 10% on gas, a huge saving on the environment would ensue. The next step is to change to a Tesla, when it becomes affordable, and the final step is to drive said Tesla to its minimum consumption.

I try to be at the last step rather than the first. Like with my house, someone must be the ice-breaker.

And, David, I actually enjoy this. It is a challenge, and I like those.

Robert

robert@bis.se:

I totally understand and follow the same approach with my Prius. That's why I wish Tesla would add an ECO mode (like the Prius) as it would help me more easily drive with greater efficiency. I can see why Tesla might not want to focus on that feature as it might detract from the high performance luxury image of the Model S but I think they could add it without detracting and folks could use it if they wanted. Also, it could be activated when the pack is down at less than 5% or 10% capacity to help you get to that next SuperCharger. It's probably on the future feature list already just maybe not at a high priority.

Good conversation all -

@ robert@bis.se

Ref. coasting, I seem to recall the great advantage with the SAAB in the olden days was the "free wheel" that exactly gave you the coasting effect you are talking about.

As to illegail...they even have a law for that in the US??? Jeeezzz!

@Robert
Thanks for posting your driving efficiency ideas. I try and drive my Tesla as efficiently as possible without foregoing the fun that driving this incredible automobile provides, and have averaged around 289 W/mile over last 3,500 miles. I will try coasting in neutral to see how that affects my energy use. I have found that I get much better efficiency on longer commutes, and have great difficulty getting below 300 W/mile on short drives of less than 5 miles. Keep posting your experiences and ideas. I appreciate your concern for reducing impacts to our planet.

@Geir T

Oh yes, and I had one and drove it very far. The main idea was that when you lifted the gas foot, the car didn't have any motor brake at all, but kept rolling without your having to change to Neutral.

Was that car outlawed in the US, I wonder?

Robert


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