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To "D" or not to "D"

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The primary reason I don't already have a Model S is because it was lacking ACC. I've been unable to find any used or "stock" vehicles that have the new radar, camera, and ultrasonic sensor hardware.

To me the dual motors and AWD was gravy - but the added wait time, cost, and 1 year delay in getting my tax credit are swaying me to "not D". Thanks for all the feedback! :smile:
 
I am in the exact same boat. I have a RWD MB with distronic plus in VA which I use 24/7 and I have been waiting for autopilot features. I was thinking of AWD but now at $5000 and 10 mile range difference It seems not worth it. So i am down to s85 or P85D. The issue with P85D is the cops in VA are crazy and over 80 is reckless driving, so in 0-4 sec your at a reckless driving ticket :(

I agree that when it snows here, the city shuts down and the highways are plowed quickly enough. The side streets are so slow in the snow that RWD has been fine. But when it was $4000 I was sure I would get the D :)

Now I do not know how long software will take to get ACC active, any insight by your talks with Tesla?'

Ideally I find a cheap demo/ used p85 with autopilot where someone wants a D.
 
Personally, I think the extra range is a BS marketing tactic.

Maybe if you are babying the accelerator the whole time, where the car mostly uses the rear motor and uses the front motor for extra regen purposes. BUT- most of the time you want to accelerate a bit and the front motor is going to be tapping into that same 85kw battery pack that the RWD/single motor cars have used. Powering two motors to accelerate is going to use more power, plain and simple. Enough power that regen wont compensate for it if you like to drive more aggressively than an 85 year old grandma.

I am calling it now, the D versions are going to have worse overall average energy usage in the real world than the RWD/single motor counterparts.

No, it doesn't work this way. The different gearing ratios mean that at a particular speed, the car can supply power to whichever motor works most efficiently at that speed. (That's where the 4% efficiency boost comes from.) So even at constant 65mph the D is more efficient than the standard S. Regen is an insignificant factor in the efficiency gain.

Also, the range improvement should be really thought of as an efficiency improvement. If you drive a certain number of miles a year, you will pay correspondingly less for the electricity. Over 100k miles, the 4% efficiency boost saves about $250 in electricity. Also, your battery pack will have a longer life because it cycles fewer times, or in a narrower range. So regardless of whether you "use" the extra range, the D does have its benefits.
 
I live in Colorado and have never put snow tires on a car - that includes FWD and 4WD and AWD. RWD absolutely needs them if there's snow on the ground or you don't move. But with anything else, All-Season work fine even with snow. That's a savings of a couple grand on tires.
 
I would get the D for resale value if no other reason. Second would be 10% more range.

Could you not put snow tires on if you had the D and save yourself $4000 on the snow tire and wheel set?

-m

they updated the website. It appears it's only 10 miles more range for the D (not the 30 miles they listed before). I would guess the EPA range for the 85D is going to be near 275 miles.
 
No, it doesn't work this way. The different gearing ratios mean that at a particular speed, the car can supply power to whichever motor works most efficiently at that speed. (That's where the 4% efficiency boost comes from.) So even at constant 65mph the D is more efficient than the standard S. Regen is an insignificant factor in the efficiency gain.

Also, the range improvement should be really thought of as an efficiency improvement. If you drive a certain number of miles a year, you will pay correspondingly less for the electricity. Over 100k miles, the 4% efficiency boost saves about $250 in electricity. Also, your battery pack will have a longer life because it cycles fewer times, or in a narrower range. So regardless of whether you "use" the extra range, the D does have its benefits.

I'd argue it is 3% and for 100k miles for me, it is more like $50 (paying 5cents a kwh off peak). So the payback is 100 times that or 10 million miles?
 
No, it doesn't work this way. The different gearing ratios mean that at a particular speed, the car can supply power to whichever motor works most efficiently at that speed. (That's where the 4% efficiency boost comes from.) So even at constant 65mph the D is more efficient than the standard S. Regen is an insignificant factor in the efficiency gain.

Also, the range improvement should be really thought of as an efficiency improvement. If you drive a certain number of miles a year, you will pay correspondingly less for the electricity. Over 100k miles, the 4% efficiency boost saves about $250 in electricity. Also, your battery pack will have a longer life because it cycles fewer times, or in a narrower range. So regardless of whether you "use" the extra range, the D does have its benefits.

Ok, well, my point is really that the motors will consume more power when you are driving in the real world- stopping, starting, etc as two motors need to draw from the same 85w capacity battery pack to get the car moving from a stop, up hills, etc. That 4% efficiency boost (to save $250 in 100K miles... LOL!) will easily be negated from the additional power draw when accelerating with 2 motors vs. 1. Maybe in a perfect testing scenario babying the accelerator would you see that 4% efficiency gain, but in the real world- I assure you two motors drawing from the same energy source will drain the battery sooner, especially when city driving vs highway cruising.
 
Ok, well, my point is really that the motors will consume more power when you are driving in the real world- stopping, starting, etc as two motors need to draw from the same 85w capacity battery pack to get the car moving from a stop, up hills, etc. That 4% efficiency boost (to save $250 in 100K miles... LOL!) will easily be negated from the additional power draw when accelerating with 2 motors vs. 1. Maybe in a perfect testing scenario babying the accelerator would you see that 4% efficiency gain, but in the real world- I assure you two motors drawing from the same energy source will drain the battery sooner, especially when city driving vs highway cruising.

They cut the motor size in half and used two (s85 vs s85d). So the total HP is still roughly the same. Just distributed. Electric motors are pretty efficient, I see no reason that two smaller motors would use more energy than one larger one. The only difference is going to be friction drivetrain losses and they are going to be variable by speed, not by acceleration.

Will see what the EPA rating says when it comes out.
 
My 85D order has been officially cancelled and replaced with a new order for the same car without the dual motors. "December" delivery according as of now. I hope that's accurate because I'd like to get the Federal credit on my 2014 returns and not have to wait until filing 2015 returns in 2016.
 
They cut the motor size in half and used two (s85 vs s85d). So the total HP is still roughly the same. Just distributed. Electric motors are pretty efficient, I see no reason that two smaller motors would use more energy than one larger one. The only difference is going to be friction drivetrain losses and they are going to be variable by speed, not by acceleration.

Will see what the EPA rating says when it comes out.
I think in ICE cars AWD is costly for the EPA rating of fuel economy because it adds so much weight - transfer case(s), driveshaft(s), etc. In the Tesla as you mentioned there's a small motor up front and some electrical connections made to it.
 
My 85D order has been officially cancelled and replaced with a new order for the same car without the dual motors. "December" delivery according as of now. I hope that's accurate because I'd like to get the Federal credit on my 2014 returns and not have to wait until filing 2015 returns in 2016.

i just turned in my leased 2013 Mercedes S550 with RWD. My prior car was an Audi A8 (AWD)... I never really appreciated the AWD until I leased the Mercedes. My thought was that AWD was a snow only thing and I'll just drive my beater SUV when it snows so what does it matter if the Mercedes is only RWD.

The S550 would spin wheels on the capital beltway if I jammed it and there was a little bit of grit. When I would merge onto my main street (well maybe try to slip in), the rear would spin, traction control took over and with cars coming both ways the big engine would slow to almost a halt governed by the traction control. It really bugged me. ;)

I had a short lease and considered the new 2015 S550 but decided it had to have AWD. My other consideration, of course, was a Tesla D. Obviously, I went with the Tesla S85D. (And then I changed my mind and changed my order to the the P85D but that's another story.)

So... everyone's taste is their own and buying objectives vary. But I wouldn't categorize the dual motors as just something that useful in the snow...

No bad choices here...
 
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+1

AWD is so much better even during moderate acceleration on dry roads since most have some amount of sand or gravel on their surfaces. Only my interest in the green aspects of the S overpowered my mantra of "always buy AWD".
 
i just turned in my leased 2013 Mercedes S550 with RWD. My prior car was an Audi A8 (AWD)... I never really appreciated the AWD until I leased the Mercedes. My thought was that AWD was a snow only thing and I'll just drive my beater SUV when it snows so what does it matter if the Mercedes is only RWD.

The S550 would spin wheels on the capital beltway if I jammed it and there was a little bit of grit. When I would merge onto my main street (well maybe try to slip in), the rear would spin, traction control took over and with cars coming both ways the big engine would slow to almost a halt governed by the traction control. It really bugged me.

I had a short lease and considered the new 2015 S550 but decided it had to have AWD. My other consideration, of course, was a Tesla D. Obviously, I went with the Tesla S85D. (And then I changed my mind and changed my order to the the P85D but that's another story.)

So... everyone's taste is their own and buying objectives vary. But I wouldn't categorize the dual motors as just something that useful in the snow...

No bad choices here...

+ 1. AWD is not just for bad weather. We'd never buy a car without AWD for the reasons you gave. The surefooted acceleration you get with AWD on dry pavement is incredible when all 4 wheels have torque. The price difference between an S85D and a P85D is "only" $20K but for that extra $20K you pretty much get a car that can keep up with most supercars and it is a great bargain for the extra performance you get. Congrats and good call on the P85D! Our P85D is on order but if we could not have afforded it, we would have waited to save a bit more to get one.
 
I'd argue it is 3% and for 100k miles for me, it is more like $50 (paying 5cents a kwh off peak). So the payback is 100 times that or 10 million miles?

5cents/kwh is quite a bargain! Here in Santa Barbara I’m paying 11 cents off-peak, on So Cal Edison's EV TOU plan. So yeah, for me more like $120 electricity savings over 100k miles, assuming I never need to charge on-peak.

Another non-negligible factor is battery life. With its combination of higher range and lower wear per mile, the D’s battery can be expected to provide about an extra year of useful life relative to the non-D. This may at least have an impact on eventual resale value, which should be factored in.
 
5cents/kwh is quite a bargain! Here in Santa Barbara I’m paying 11 cents off-peak, on So Cal Edison's EV TOU plan. So yeah, for me more like $120 electricity savings over 100k miles, assuming I never need to charge on-peak.

Another non-negligible factor is battery life. With its combination of higher range and lower wear per mile, the D’s battery can be expected to provide about an extra year of useful life relative to the non-D. This may at least have an impact on eventual resale value, which should be factored in.


A year? Going back to the 3% improvement in efficiency, are you talking 30 year expected life and the 3% gives you an extra year? And even that would completely neglect calender life degradation. If part of that 3% came from improved regen, that of course is increasing cycling rather than efficiency so it wouldn't count.

So help me out here - where are you getting a year? We still probably have 5 years before we have meaningful life expectancy numbers since the life seems to be so long.

When it was 10%, I'd get a D almost for that alone. At 3%, not so much. Now maybe it is really 4%.

I'm with the consensus. On a fast car, AWD is always helpful. Rocks, sand etc. And at $4k, I didn't expect to see many non-Ds. But $5k hit a psychologic barrier for me.
 
I'd like to point out another performance aspect of AWD. In my S85, when turning onto a road with traffic I have to be very careful with the accelerator. It accelerates great on the straight, but looses grip turning into traffic. I expect the D to be much better in this case, which happens several times during my daily commute.

The issue with tire circumference on AWD is related to the drive train. With a single power source AWD, all tires must be very close tolerance or they will fight each other and wear faster, cause drive line strain, and affect traction. With the D, any wheel can rotate at a different speed without ill effect. This happens more dramatically with the different track of the wheels in a tight turn. The computers will decide how much difference is too much.
 
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