Rear Wheel Drive P85 is a Missed Opportunity for Tesla

[Gizmotoy]

Oh boy. It's complicated. It's basically the difference between having traction and having lost traction (and therefore creating slip and a thin layer under the tire that acts like a liquid from a friction point of view).
So as long as you have traction, a front wheel drive (or the front wheels of an AWD) will create both thrust and steering (and better steering than unpowered wheels, btw). And that's why I said the simplistic statement was wrong.
But what you mention here is of course correct, once you get the wheels to slide (either by steering too hard or by accelerating too hard) you lose both, steering and thrust.
This is why a good traction control on an AWD is so critical - and if you have one engine and are using differentials to prevent front wheel slip, the car will most likely lose steering when you apply more and more thrust. But with a separate front motor that has a very responsive traction control, you can prevent the wheels from slipping and therefore maintain BOTH steering and thrust - within the boundaries of the friction that is available.

Edited to add:
One way to think about this is that the "grip" that provides steering are the longitudinal edges of your profile / tire. The grip for thrust is primarily the cross edges. So it is not true that you have one pool of grip for both axes. It's just true that once you slip and create the liquid-like situation, both types of edges lose friction.

All I know is lies! :wink::biggrin: Seems logical, thanks for the lesson!

 

[dirkhh]

All I know is lies! :wink::biggrin: Seems logical, thanks for the lesson!

Any time. I'm here all week. I work for reputation points :-D

 

[richkae]

Oh boy. It's complicated. It's basically the difference between having traction and having lost traction (and therefore creating slip and a thin layer under the tire that acts like a liquid from a friction point of view).
So as long as you have traction, a front wheel drive (or the front wheels of an AWD) will create both thrust and steering (and better steering than unpowered wheels, btw). And that's why I said the simplistic statement was wrong.
But what you mention here is of course correct, once you get the wheels to slide (either by steering too hard or by accelerating too hard) you lose both, steering and thrust.
This is why a good traction control on an AWD is so critical - and if you have one engine and are using differentials to prevent front wheel slip, the car will most likely lose steering when you apply more and more thrust. But with a separate front motor that has a very responsive traction control, you can prevent the wheels from slipping and therefore maintain BOTH steering and thrust - within the boundaries of the friction that is available.

Edited to add:
One way to think about this is that the "grip" that provides steering are the longitudinal edges of your profile / tire. The grip for thrust is primarily the cross edges. So it is not true that you have one pool of grip for both axes. It's just true that once you slip and create the liquid-like situation, both types of edges lose friction.

Thanks for the education. I appreciate the correction.

 

[MartinAustin]

My $0.02 on the original poster's message... I was sad to see my own car get discontinued less than year after I got it! But after months have passed allowing me to reflect on it... I disagree with your main point. I believe Elon is a big fan of the traction & grip you get from AWD on dry surfaces, wet surfaces, puddles, grass, snow, ice... everything. It's ideal for cars not suited to the track - since cars not suited to the track are driven by 99% of us regular folks, and one of the things we are interested in the most is... safety, especially for the family. AWD is a great help no matter where you are... eventually it rains in Texas, and you may need to get out of the way of someone coming at you! The deletion of the RWD products on October 9th falls firmly in line with this philosophy (while also increasing ASP, as many have observed).

Take the Model X. You will recall, it had RWD and AWD variants, but they decided to drop the RWD version. Range may have been a factor with that, but I believe the family-oriented target demographic for the "X" was also important, and so, safety is paramount. People looking for safety see "AWD" as one more checkbox with a check in it. Look at Subaru's TV commercials these days... they're all about being parents.

What does this leave for the 1% who like to drive the same car on regular roads AND the track? If you are in a P85 right now and think it's great, and will become a classic, well, come on, it's not really perfect, is it? It can't track for very long. It's like an understudy who never gets to go on stage in front of the crowd. If you are lamenting the deletion of the P85/P85+, come on... it has 4 doors and a seven-seat option. Not really made for the track. Maybe that's why we will think of it as a classic... because it is not perfect. I love the acceleration but I hate the traction-slip and fishtailing once the tires are no longer new. (Have not taken it to a track yet)

What I believe Tesla wants to do going forwards is keep road cars and AWD together as much as possible, with few or no RWD variants. This promotes range and safety. Only cost to the customer will force them to provide RWD... the $35,000 announced price of the Model 3 will be a RWD version, but ironically its 200-mile range will be shorter range than the Model 3 AWD variant on the same battery. Even if the equivalent AWD Model 3 can do (say) 220 miles, Tesla will still produce the RWD version because they are hamstrung by price. But they will still use their powers and steer unsuspecting Model 3 buyers towards the AWD variants when possible - because it's a profit center - but also because it is safer in more circumstances, and Elon wants his precious Tesla brand to build a reputation for good roadholding in bad conditions. (and I don't blame him... and IMO this process is already well on its way)

IMO - the next generation of the Roadster will be where Elon next produces an all-out sporting car, whose driver takes responsibility for his safety and the car will respond in a sporting manner when given the right input from the driver. RWD will probably come high on the list of features.

If you listen carefully into the most recent earnings call, Elon talked about variations of the Model 3 platform that, initially, were considered for an early start along with the 200-mile $35,000 variant, but were put on the back burner until that main Model 3 car was safely into production. After this point, "schedule and production volume issues" would be less important, so more "out there" designs might appear on the Model 3 platform. Perhaps the next generation Roadster is one of these lower-volume variants; more expensive to buy of course, with larger motor/invertor combo, beefed-up drivetrain cooling for endurace, open-top w/ roll bar, 2 seats, not much storage space, etc. - very different to the form factor of the Model S.

Further out into the future, when Tesla gets to work on their Generation 4 car, which unless it's a pickup truck I would assume is something that would be in the Honda Civic category and appeal to even more people with a $20,000 price... Tesla will still continue with the same tactic. They'll want to put AWD into it but they'll have to put out an RWD variant at the bottom of the range, for reasons of cost.

BWA HA HA this is my 666th post...

 

[brianman]

Well I've done sustained 100mph for 80 miles straight in my P85 so I can disprove that theory.

Not sure which theory you're disproving, but 100mph @ steady is quite different from up/down track driving.

- - - Updated - - -

110kw battery announcement

Nitpicker's corner: a 110kW battery Model S would suck, but a 110kWh Model S would be a nice improvement.

- - - Updated - - -

You don't understand Tesla very well, I think. Tesla made a calculated decision to eliminate the P85 because it wanted to push all of those buyers into the even more expensive and higher margin P85D. The move worked out well for Tesla. Judging by the number of used P85s on the market, it was quite a popular configuration.

I think you're overthinking it. As long as they have buyers "red-lining" their production capacity they could make every vehicle off the line a P85D and make all the options standard (with base price increase).

Instead they've continued (/renewed?) the practice of setting nearer delivery times for higher priced flavors. At the limit, they would be deliverying only P85Ds -- so clearly demand for P85Ds is not saturating the current production capacity. So then it slides to "Should we deliver S85D next or P85 next?" My suspicion is that the profitability of the S85D is higher -- and they get Model X telemetry data from S85D.

So (my turn to overthink it)...

Let's imagine the profitability per flavor is:
P85D > S85D > P85 > S85 > S60 > S40

They killed the S40 because the cost wasn't worth the benefits for a relatively small customer segment.

Likely they let go of the P85 segment because either P85D or S85D "covered" most of those customers, and the profitability loss relative to a delivered S85D and the factory overhead couldn't support its continued existence.

 

[Evbwcaer]

Maybe Tesla will offer an option to turn the front motor off for the RWD fans. Better yet, a slider allowing you to go pure RWD, pure FWD, max range, or whatever proportion you want of the two.

 

[AWDtsla]

RWD is quaint. I could go on for a long time why this is so, and the arguments won't be taken properly. I guarantee you it's quaint. If you really want more RWD feel, it's near trivial for Tesla to have a software update that sends more (or ALL) torque to the rear wheels. But this would just be silly.

 

[tomas]

I know this is rendered inaccurate by price increases etc. along the way... I did my occasional dive into the design studio with sticker by my side to compare my purchase price/features on 2012 P85 vs. today's equivalent.

My 2012 P85 as equipped with equivalent of today's premium interior, pano roof, sound studio, active air, 21" wheels, tech package: $99,600

Equivalent 85D (minus P, plus Dual and driver assist features and next gen seats): $110,820 net increase $11,220
Equivalent P95D (plus Dual and driver assist features and next gen seats): $128,920 net increase $29,320

That's 11% and 30% more money, respectively.

Reaffirms happiness with P85. I realize the later one bought their P85, the more this gap closes... but I'm now feeling I got a decent deal... including the incalculable value of driving the car 2+ years.

 

[SilverSpark]

Just priced a new P85D optioned like my May 2014 P85+ and got a price difference of $5,200; a lot of $$ for sure, but low in terms of % of total cost. While I love the driving characteristics of RWD, I've also owned and enjoyed AWD cars, and would have no issues replacing my + with a D. True, the frunk is way smaller, but I seldom even open the frunk.

The main reason I opted for the + was its surprisingly well executed combination of ride and handling, which I felt was by far the best Tesla offered at the time (ordered March 2014), and which still impresses me after almost 1 year of driving. (I feel this is an underrated virtue of the car.) So for me, the missing link in Tesla's model lineup remains pretty much the same as it's always been: the lack of a separate option for a performance/premium suspension setup. BMW has offered this for years, and I believe other premium manufacturers do as well. Why not Tesla?