Should Tesla make a “Track Edition” Roadster?

[Peteski]

Weight does not effect Tesla handling as much as with other cars, as the heavy battery is mounted so low in the chassis.

Elon has mentioned that they have been making significant breakthroughs in their battery technlolgy that are much lighter, less expensive and even longer lasting.

Perhaps they will be first used in the much more expensive New Roadster to further enhance its track performance.

Tesla did pretty well with the performance of the P100D, but from my perspective they have knocked it out of the park with the latest Model 3 performance pack. They are becoming very competitive with other manufacturers track cars, especially on the shorter courses.

Believe their final challenge will be endurance racing, where the gassers larger fuel tanks still give them the advantage.

For sure a low CofG is a valid point, but it only goes so far when you keep on increasing the weight. The Model S is perhaps at the limit of what is acceptable for weight vs handling in its class. The Porsche Panamera has sharper handling for example and only weighs a little less. These are both big cars optimised more for comfortable cruising than ultimate handling performance. It's certainly no coincidence that Porsche's first EV is in this larger class too as they were acutely aware of the weight penalty in producing a more focused sports car. As their chief designer stated in a recent interview, the weight penalty is less critical in large sedans and SUVs.

The Model 3 Performance appears to be a reasonable compromise, but again it's right at the top end of the weight range to be truly competitive in handling against its main rivals. In both cases the electric drivetrain is their main advantage and their excess weight remains a signficant handicap to overcome. The Roadster is pushing that to the extreme with twice the battery of a P100D and potentially many hundreds of kgs of weight penalty against its competitors. Brushing that extra weight off is not going to be so easy unless you really don't consider handling to be an important feature of this car.

 

[jaguar36]

I think its worth at least considering the possibility that the new Roadster will use a new cell chemistry that has substantially higher energy density. We know Tesla is working hard to improve the cell chemistry and the Roadster would be the perfect place for it to debut. It could absorb the likely higher cost per kwh and the low production rates.

I think this is far more likely than the SpaceX option amounting to anything.

 

[Peteski]

I think its worth at least considering the possibility that the new Roadster will use a new cell chemistry that has substantially higher energy density. We know Tesla is working hard to improve the cell chemistry and the Roadster would be the perfect place for it to debut. It could absorb the likely higher cost per kwh and the low production rates.

I think this is far more likely than the SpaceX option amounting to anything.

Of course that would be a colossal game changer rather than a fairly pointless sideshow.

 

[CarlK]

I see you are quite the "expert" here so I'm not getting drawn into another pointless internet debate about the basics of vehicle handling and the history of the 911, your summary of which above is frankly laughable and not worthy of serious comment.

Ignorance is bliss as they say!

Edit: As far as the relative dangers of "active systems" goes, it's one thing using systems to "optimise" the inherent grip you already have e.g. torque vectoring, stability control, ABS etc and quite another to introduce a system that actively "increases" your cornering/braking forces e.g. thrusters and active aero elements. These introduce a whole new level of danger for fairly obvious reasons. A failure of a thruster during a high speed cornering event would not end well.

You pooh-pooh'd Tesla because it uses or will use the "dangerous" "active system" to achieve the performance goal. No I'm not an expert on Porsche but I think Porsche is. This is from Porsche itself:

"Porsche Stability Management (PSM)
All 911 models are equipped with enhanced Porsche Stability Management (PSM) as standard. PSM maintains stability even at the limits of dynamic driving performance. Sensors continuously monitor the direction, speed, yaw velocity and lateral acceleration of the car. Using this information, PSM is able to calculate the actual direction of travel at any given moment and initiates strategic braking of individual wheels to prevent you from deviating from your intended line.

Under acceleration on inconsistent surfaces, PSM improves traction using the automatic brake differential (ABD) and anti-slip regulation (ASR) functions. The result is a high level of driving stability and safety – and extraordinary agility at the same time."

Everyone relies on active systems now. The only difference is by nature of the fast feedback loop it can do much better, or shall I even say safer, for electric vehicles than it can for ICE cars. As for the thruster it's nothing but a new kind of active system. No one is using it of course but then again no one has thought of landing a rocket on a floating barge (that relies on thrusters) is possible before that was shown to them. Again the reason that we are not still using stone tools is only because there were always a few who were willing to think outside the box.

 

[jaguar36]

All later 911s are very well balanced.

Until recently 911s had snap oversteer that could hardly be classified as 'well balanced' In fact here's a quote from Hagerty:

"The snap-oversteer that plagued earlier 911s was even more dangerous.."

 

[SSonnentag]

I have no doubt the Roadster will come with track mode. Model 3 track mode was likely implemented as beta testing for the Roadster.

 

[Peteski]

You pooh-pooh'd Tesla because it uses or will use the "dangerous" "active system" to achieve the performance goal. No I'm not an expert on Porsche but I think Porsche is. This is from Porsche itself:

"Porsche Stability Management (PSM)
All 911 models are equipped with enhanced Porsche Stability Management (PSM) as standard. PSM maintains stability even at the limits of dynamic driving performance. Sensors continuously monitor the direction, speed, yaw velocity and lateral acceleration of the car. Using this information, PSM is able to calculate the actual direction of travel at any given moment and initiates strategic braking of individual wheels to prevent you from deviating from your intended line.

Under acceleration on inconsistent surfaces, PSM improves traction using the automatic brake differential (ABD) and anti-slip regulation (ASR) functions. The result is a high level of driving stability and safety – and extraordinary agility at the same time."

Everyone relies on active systems now. The only difference is by nature of the fast feedback loop it can do much better, or shall I even say safer, for electric vehicles than it can for ICE cars. No one is using the thruster of course but then again no one has thought of landing a rocket on a floating barge (that relies on thrusters) is possible before that was shown to them. Again the reason that we are not still using stone tools is only because there were always a few who were willing to think outside the box (even though there were always a lot more who were willing to pull their legs).

You seem to have a problem understanding the difference between stability control, which makes the car easier for an average driver to maintain control of and a system that augments the actual grip level available i.e. thrusters. The former doesn't really change the fundamental handling or grip level of the car, it just optimises the available grip and makes it foolproof. The latter increases the performance envelope and a failure would have instant and serious consequences.

Also don't be fooled into thinking Porsche have poor handling without PSM. Most of the really quick laps by professional drivers are with PSM switched off!

 

[Peteski]

Until recently 911s had snap oversteer that could hardly be classified as 'well balanced' In fact here's a quote from Hagerty:

"The snap-oversteer that plagued earlier 911s was even more dangerous.."

Seriously?

 

[CarlK]

Seriously?

How ignorant one could be.

You seem to have a problem understanding the difference between stability control, which makes the car easier for an average driver to maintain control of and a system that augments the actual grip level available i.e. thrusters. The former doesn't really change the fundamental handling or grip level of the car, it just optimises the available grip and makes it foolproof. The latter increases the performance envelope and a failure would have instant and serious consequences.

Also don't be fooled into thinking Porsche have poor handling without PSM. Most of the really quick laps by professional drivers are with PSM switched off!

This is the right place to say "seriously?". Your beloved 919 race car has more complicated traction control than most other cars out there.

 

[Peteski]

How ignorant one could be.



This is the right place to say "seriously?". Your beloved 919 race car has more complicated traction control than most other cars out there.

My beloved 919? You've totally lost the plot of this discussion and turned it into a pissing contest when I was making a very simple point about the fundamentals of vehicle weight, which you consistently fail to grasp.

 

[CarlK]

My beloved 919? You've totally lost the plot of this discussion and turned it into a pissing contest when I was making a very simple point about the fundamentals of vehicle weight, which you consistently fail to grasp.

No one has argued weight is not "a" factor. You're the one who's continuously arguing technology can not be another and increasingly more significant factor. You're only digging a hole you can't get out by denying it (like the comment professional drivers don't need active system). Even your beloved, yes beloved, Porsche relied on technology to get to where they are today. You were insisting the Roadster can not be one of the best handling cars without even understand what kind of technology will be put in the car. Can you at least wait for a while to get a good idea of what it really is before that silly "oh it will not work because it has a heavy battery" conclusion?

Don't think either of us will change the view even if we continue this for another 100 posts. Let's wait till, hopefully, 2020 to see how the car really is like. I think you, and even I, will be surprised. Technology can do wonders beyond what us layman could imagine. I'll let you to have the last say if you wish.

 

[Maxfaxdude]

I strongly suspect that the 2020 Roadster will be anything but a letdown in every metric. Be it top speed, handling, weight, range, acceleration, maintenance costs or overall value, the Roadster will be THE supercar of production supercars. And others will have to follow Tesla's lead or face fading away or dying off altogether. My belief is that Musk will use a lighter-weight more energy-dense battery technology that is being or has already been developed but not yet put into production to power the new Roadster. Coupled with the Space Ex option, when the Roadster debuts, it will be a watershed moment in automotive technology and innovation.

 

[Peteski]

No one has argued weight is not "a" factor. You're the one who's continuously arguing technology can not be another and increasingly more significant factor. You're only digging a hole you can't get out by denying it (like the comment professional drivers don't need active system). Even your beloved, yes beloved, Porsche relied on technology to get to where they are today. You were insisting the Roadster can not be one of the best handling cars without even understand what kind of technology will be put in the car. Can you at least wait for a while to get a good idea of what it really is before that silly "oh it will not work because it has a heavy battery" conclusion?

Don't think either of us will change the view even if we continue this for another 100 posts. Let's wait till, hopefully, 2020 to see how the car really is like. I think you, and even I, will be surprised. Technology can do wonders beyond what us layman could imagine. I'll let you to have the last say if you wish.

Okay, so we at least can agree weight is a factor. Where we differ greatly is in what we consider to be fundamental factors in vehicle handling. As an experienced vehicle dynamicist and race engineer I know that weight is a fundamental parameter and central to any vehicle dynamics model. You can toss as many straw men in front of that simple truth as you wish, but it doesn't change the fact.

This idea you are putting forward that Porsche 911, 919 etc only handle well because of stability control systems is totally inaccurate and misleading. The stability systems on their current road cars are often switched off for serious track use simply because they dumb down the performance envelope for safety in the hands of average drivers. Switching them off does make them harder to drive on the limit, but the limits are a little higher without them. Here's an interesting article about the Panamera Nurburgring lap record:-

Meet the man who set a Nürburgring lap record in a Porsche Panamera | Autocar

"Kern says advances in suspension and tyre technology and the car's lighter weight were of a huge benefit" (in comparison to the heavier gen 1 Panamera)

"For the fast lap, the car was switched into its most extreme driving mode, Sport+, and the Porsche Stability Management (PSM) was turned off." (as is usual practice for a pro driver aiming to set a fastest lap)

With full blown race cars like the 919, traction control, ABS etc is calibrated specifically for racing (their main benefit in racing is tyre wear management rather than handling) and these systems are nowhere near as conservative or foolproof as equivalent road car systems. I worked extensively with traction control systems in F1 before it was eventually banned and there again it was all about tyre wear rather than handling. Without traction control they would be harder to drive and certainly harder on their tyres, but the basic handling would be the same. The fundamental reasons why the 919 is so fast are its ultra-low weight (it's nearly half the weight of the road going 918), high downforce and power, all coupled with a stiff (as in torsional chassis rigidity and suspension installation stiffness) race-bred chassis. It's electronic systems are really just the icing on the cake, not key fundamentals.

Now don't put words into my mouth about the Roadster. I'm merely saying that weight is highly likely to be the major issue for it to overcome in terms of ultimate handling performance. Now if by some miracle they can bring this car in at 1700-1800 kg with a 200 kWh battery (i.e. match the weight of the Nio EP9 with it's much smaller battery and carbon race chassis) then it could be sensational with all the inherent advantages of an electric drivetrain. But if it ends up well over 2000 kg, which I think is almost inevitable, then it's going to be a real issue setting competitive lap times. Basically much the same problem Bugatti have in that regard with their 2000 kg Chiron. That doesn't mean it will not be a great road car, just not a complete all-rounder.

As a final thought, maybe we can agree that it would require a major breakthrough in technology to make weight an unimportant factor in vehicle handling. But I'm not putting any money on this SpaceX package being the answer. You see unlike you, I'm not a "layman" when it comes to vehicle handling and specifically race car handling. It's my chosen profession and I've been involved at the highest level for a long time. The real meaningful breakthrough will be in making significantly lighter batteries and if the Roadster arrives with some amazingly light 200 kWh battery, then that will be far more impressive than any bolt-on "rocket" system.

I'll leave you with these recent quotes from Porsche's R&D chief:-

"Fully electrified sports cars would work very well for longitudinal acceleration,” says Porsche R&D boss Michael Steiner, “but the weight disadvantage is in the handling."

“When this could happen depends on the evolution of battery power and cell density.” (in response to the intro of an EV 911)

"Porsche has built an all-electric Boxster prototype to test the concept. It performed well, but delivered lower track times because of a heavier kerb weight that also affected roadholding."

 

[Cloxxki]

It's not just for range. Matter of fact it's not for range at all. It's to have enough power output to get the acceleration and top speed. It will also help track longevity. It's better to have more cells and each work less hard at high cruising speed. As for weight the Model 3 performance in (tuned) track mode already matches track time of the much lighter Cayman GT4 which was designed for track purpose.

Only true if the quarter million flagship is to have the same "lowest cost on the market" cells as the Model 3. Which is kind of insane in itself.
Rimac C_Two will do better sprint and top speed with just 120kWh. Smaller could and would work even better, just at a cost of range. With one of the motors on board an efficient one, a 100kWh sport car with power cells and lighter chassis allowing for the performance numbers boasted would also average very similarly to Model 3...for 400+ miles of range. Would that suffice? Oh, and power cells suffer from heat buildup much less. Charge faster. Imagine a 5 minute 5-80% charge (300+ miles).

 

[Brando]

@Peteski
roadholding - can you offer some insights on tires? recommend articles? or perhaps a book?

thanks for any insights

 

[CarlK]

Only true if the quarter million flagship is to have the same "lowest cost on the market" cells as the Model 3. Which is kind of insane in itself.
Rimac C_Two will do better sprint and top speed with just 120kWh. Smaller could and would work even better, just at a cost of range. With one of the motors on board an efficient one, a 100kWh sport car with power cells and lighter chassis allowing for the performance numbers boasted would also average very similarly to Model 3...for 400+ miles of range. Would that suffice? Oh, and power cells suffer from heat buildup much less. Charge faster. Imagine a 5 minute 5-80% charge (300+ miles).

Range that high, especially in a sports car, can not be the reason, or a reason, for having the 200 kWh battery. Batteries could, and like you said probably will, get lighter but I doubt improvement can be very significant in just two years. Then again who knows? Without knowing all parameters those, max power output and battery longevity, are only things I can think of. Another reason would be Tesla does not know what it's doing. That I kind of doubt is the case.

One more thing is cars like Rimac are purposely built limited quantity hypercars. On the other hand people who buy the Roadster will also demand all the luxury and creature comfort in a car they likely will be driving everyday. It's not exactly comparing apples to apples. Tesla will never make a hypercar beyond the Roadster although I always have a thought that it could work with some others in that area. Koenigsegg is one that comes to mind. Koenigsegg seems to be a down to earth engineer not to mention a Tesla fan and Model S owner. Matter of fact he said he got inspiration from Model S in the implementation of single gear direct drive in his latest hybred Regera. It's not without precedents that a hypercar manufacture getting drive train from another company. This should work well with both Koenigsegg and Tesla. Just a wild thought of course.

 

[Peteski]

@Peteski
roadholding - can you offer some insights on tires? recommend articles? or perhaps a book?

thanks for any insights

Hi,

This is the book I first studied at Uni back in the late 80s. It's a little dated today in its examples but it's still a very good intro to the subject of vehicle dynamics and covers the basics very well. I still refer to it occasionally myself:-

https://www.amazon.co.uk/Fundamenta...8-1&keywords=fundamentals+of+vehicle+dynamics

Tyres are a vey complex subject and not surprisingly one of the most important parts of the car. Even the tyre manufacturers don't fully understand the highly complex nature of the contact patch with such a wide variety of road surfaces and ambient conditions. It's a very dynamic situation and requires expertise in many fields from chemistry to mechanical engineering. It's one of the reasons why all vehicle manufacturers leave tyres to specialist suppliers and a good reason why it's always best to stick to the premium tyre manufacturers when choosing tyres yourself. In F1 we spent an awful lot of time and money on tyre testing and development of thermal dynamic tyre modelling, but there was still always an element of trial and error in the end. But if there's one thing to know, it's that tyre pressures are critical to cornering grip and traction. As a good rule of thumb, the lower pressure the better until you start having safety issues with sidewall fatigue. Again this is yet another reason why you don't want an excessively heavy car that requires 40+ psi in the tyres to run safely. As an extreme example, F1 tyres run at around 17 psi hot. It's also worth mentioning that the marketing trend toward ever bigger and lower profile tyres is just that. Most tyre engineers agree that the ideal sidewall profile is something around 50-55%, yet we now regularly see 30 series performance tyres on massive rims. It's all marketing led and the engineers do what they can to make those ultra-low profile tyres work in real world conditions. But sales matter and the industry has no choice but to cater for that cosmetic preference. Years ago when I was working in BTCC (British Touring Car Championship) we worked with Michelin in moving from 18" to 19" wheels (marketing led move again) and it took nearly a year of development testing to get the 19" wheels close to the performance level of the older 18" standard. We got there in the end and continued to improve, but the larger wheels didn't help at all! Of course now we regularly see 20 and 21" rims and that requires a lot of compensation in the suspension just to make the ride vaguely acceptable. I note the Porsche 919 race car uses 18" rims for ultimate performance, while the road going 918 sits on 20/21" rims. Also note that a lot of track day warriors downsize to 18" or 19" on their GT3s etc. Makes sense on a number of levels.

Out of curiosity I just had a quick look at the Wiki entry for "automobile handling" and while some of it is reasonably accurate, it's very badly worded and misleading in places. Certainly justifies the content warning flag!

 

[Peteski]

Another reason would be Tesla does not know what it's doing. That I kind of doubt is the case.

Probably more likely a case of hitting the headline performance figures without worrying much about other consequences at this point. It appears to have had the desired effect by making headlines, but I'm certainly not the first to see beyond the raw acceleration and top speed figures. We now have to wait a couple of years for the end result. If it breaks new ground on battery density then that would be amazing, but I will be disappointed if it's just a huge heavy battery of the current type. There's a very good reason why 100 kWh is a sensible limit for current battery density.

 

[Brando]

Saab mentioned how much effort went into "finding" the right tyre for the 900. The tyre was considered an important part of the "suspension system". I thought perhaps it was more "Michelin tire marketing" than actual engineering considerations.
185/65 standard to 195/60 for performance SPG version. 1980s, so I'm not sure about the sizes.

Last tires 205/60 for cosmetic reason - my bad, performance driving not a consideration really - hydroplaning increased with this non Michelin wider tire - confirms to my mind Michelin are really great tires and Saab was correct, I should probably stay with specified tire for best results for street safety.

Thanks for book info. Perhaps you should consider Wikipedia editing?

thanks again

 

[Peteski]

Saab mentioned how much effort went into "finding" the right tyre for the 900. The tyre was considered an important part of the "suspension system". I thought perhaps it was more "Michelin tire marketing" than actual engineering considerations.
185/65 standard to 195/60 for performance SPG version. 1980s, so I'm not sure about the sizes.

Last tires 205/60 for cosmetic reason - my bad, performance driving not a consideration really - hydroplaning increased with this non Michelin wider tire - confirms to my mind Michelin are really great tires and Saab was correct, I should probably stay with specified tire for best results for street safety.

Thanks for book info. Perhaps you should consider Wikipedia editing?

thanks again

Interesting anecdote. IMO Michelin are the world leader in performance tyre technology. That's not to say other premium brands lag behind (they all have their pros and cons), but Michelin have a great R&D team and motorsport history. Working with Michelin in BTCC and later F1 was very interesting. I worked with Bridgestone in F1 too, but they were a lot more secretive with their tyre development and didn't share much data with teams. Michelin on the other hand were very open and inclusive and I think that helped both parties. It was a shame to see Michelin leave F1 in the end. Pirelli and Continental make great tyres too and I would trust any of those brands on my cars.