required reading for this thread - I know @Needsdecaf already posted this - but I’d like to suggest it’s really worth your time and will help understand the sea change going on right now in the industry - and is topical given the EPA numbers we are discussing. Tesla is the leader in this space.

​​​​​​https://www.roadandtrack.com/car-cul...ore-than-ever/

 

I do not think it is related to aerodynamics. EPA test speeds are too low for that. Weight however matters a lot.

The Road-Load Horse Power @ 50mph estimates the total power needed to keep the vehicle's speed at 50mph, so it is the function of air drag and rolling resistance.

Tesla Model X Long Range preraven; 265/45R20 (F) 275/45R20 (R) 13.48 horsepower
Tesla Model X Long Range preraven; 265/35R22 (F) 285/35R22 (R) 15.85 horsepower

Audi E-Tron: 255/50R20(F) 265/45R21 (R) 13.4 horsepower

(Audi has lower air drag in this equation - smaller frontal area, however the linear component is slightly higher, which is partially the rolling resistance. This is why it's so close to the Model X R20)

 

The other sobering consideration is that EV owners don't charge their EV's to 100% on a routine (daily) basis. Typically, EV's are only charged to 90% to help extend battery life. This would obviously result in only about 180 miles of "daily range" on a vehicle with 200 miles of "EPA Range".

Additionally, the times when we DO charge to 100% is only in anticipation of an extended (long range) driving day. Even then, for days you intend to do a cross country trip (starting @ 100%/200 miles), you would only likely charge to 80% (160 miles) at each enroute station in the interest of time and efficiency. Typically, station charging times are quoted at 80% capacity because of the declining rate for topping off. So long distance planning would generally result in station planning at LESS than 160 miles apart for safe planning on your 200 mile car.

Using the "80% rule", your 200 mile EPA range is now effectively somewhere around 140-150 miles MAX between stations on long trips.

 

I just finished up delivery training on the Taycan and got to drive the Turbo S version in Atlanta yesterday. The car is amazing and has incredible speed, handling, ride and a fabulous feel to it. Steering feels 911 like, the car hides it mass incredibly well and I even liked the goofy electronic sound generator. I would choose it over any Panamera and if I needed 4 seats occasionally it could be a legitimate 911 switch. The car is not perfect and there are areas I am sure will improve as time goes on. I think anyone that has talked to me for more than 5 minutes know I am not a kool aid drinker for the brand and try to give honest assessments as I see it.

What the Taycan doesn’t have is any regen like most electric cars I have driven UNLESS you push the brake pedal or put it in a different mode. The car has a .22-.25 coefficient of drag depending on wheels so it’s a slippery shape. The coast mode is how we drove the cars most of the time which gives little regen but felt best to me and my driving partner. It’s not going to be great for extending range obviously. You could switch it to a higher regen mode but again it’s nowhere near as aggressive as when you use the brakes and you regen properly.The high regen mode felt like you had left the car in 3rd gear when you come off the go pedal. It’s not a one pedal car though and I am sure this killed the EPA rated range. In our driving the car we would have gone over 200 miles easily and I think once folks get these cars next year they will find this to be the case as well. The 4S should give the longest range but I think on this EPA cycle it still will not be much better than 210 ish miles. My 2 cents for what it’s worth guys.

 

True but according to Porsche and their independent testing if you drive it like a grandma within 5mph of the speed limit you'll do substantially better!

 

If the lack of standard regen is the reason for the low EPA rating then why the hell didn't Porsche figure out this would be an issue. Adding regen is a software update. Make it an option and solve the problem.

However, I'm skeptical that regen is the only factor. The Etron has a similar range and as online (YouTube driving on the same course and conditions) testing has shown it has terrible efficiency compared to the Model S/X. So I understand so quick test drives show promising numbers, but that isn't real data. They need to be compared under the same conditions. So far the only comparison we have is the EPA and Euro ratings which show the Taycan being the least efficient.

 

Another, and perhaps main, reason 90% is a good daily number is for efficiency. At 100% charge, regen is very limited - because there is no place to store potentially recoverable kinetic energy. So friction braking gets used much more often, which is wasteful, until the state of charge drops a bit and regen can work again. For example the Bolt EV has a 'hill top' charging mode. It limits the maximum charge a bit. That way if you charge at your home overnight up in the mountains, then drive down hill to work in the morning, you'll be able to recover that energy for use the rest of the day.

 

I don't buy it either. Regen can help a lot in city driving - where you are constantly stopping and going. But much less so on the highway - where you are cruising at a relatively constant speed.

 

I agree that this is not related to regen. Even though the regen was set to Level 0 for the E-Tron and Standard regen was used for the Tesla Model X. But on the dyno it doesn't matter much.

As I mentioned earlier the regen converts the kinetic energy to electric energy.

Kinetic energy of the car on the road is large K=1/2*mass of vehicle * speed^2. However very little on the dyno since the car is stationary, only the wheels are spinning.

Here is a rough calculation:


K_straight_line=1/2m*v^2
K_rotating_mass=1/2mr^2w^2

mass of car = 2500kg
v = 50mph = 22.352m/s

mass of wheel = 25kg just a guess
radius for center of mass = 0.25m just a guess
w @ 50mph for 255/50R20 = 22.352m/s / ((255mm*50%*2+20")meter*pi) = 9.325 1/s


Kinetic energy of a car moving at 50mph = 0.5*2500*22.352^2 = 624.5kJ = 173.5Wh

Kinetic energy of 4 wheels on a car moving at 50mph = 0.5*4*25*0.25^2*9.325^2 = 0.27kJ = 0.075Wh


EDIT: OOOPS one thing I forgot. The dyno can simulate the weight of the car at acceleration, and it might be able to simulate the weight for the deceleration as well. I have to check this. It's not trivial. For acceleration the dyno needs brakes only, but to simulate regen/deceleration, it needs to be driven by electric motors.

 

the Porsche designers were pretty clear they hated 1 pedal driving and wanted a more traditionally Porsche driving experience. They can certainly software update improvements here, but I don't think that helps with the EPA. The EPA tests your default configuration turning the car on. This is why it's such a pain to turn auto start stop (***) off in a 992 911.

yeah, I don't think the regen is the primary factor here. Early reviews compared W/km with the model S, and these numbers aren't far off what the EPA measured. That was with very aggressive "journalist gets car for a day, GO" driving, but it still compared unfavorably to the model S. Tesla has spent more than a decade optimizing the power efficiency of everything. Power train, thermal management, AC, entertainment system, braking. By all accounts, their thermal management is better, and everything else has had years of tuning and incremental improvements.

 

Not sure if mentioned before, but EPA test is run on a dyno. Not sure how wltp is done, but the other test seems to be based on real world driving.

https://www.myev.com/research/buyers...ctric-vehicles

 

Really? So how did it win SCAA it’s first year against Porsches?

 

Range does matter - despite the porsche apologist claiming otherwise - and I can prove.

Range matters soooooo much that Porsche ponied up actual cash money to pay someone else to cover their *** - there is _NO_ other explanation. If range didn’t matter Porsche (the most profitable car company in the industry) would not have paid someone for an independent test.

Now no one on this forum knows why the Taycan sucks sooo hard (201 EPA rating) but it does in fact suck, and it sucks soooo hard it’s not competitive. Results like this are not excellence in engineering, they are mistakes made by neophyte in a changing industry that only bears a passing resemblance to the prior state of the art.

Porsche just admitted they can’t match Tesla, and their secret sauce isn’t as effective in this new world.

I have faith they will rise to the occassion, but please let’s dispense with the BS that EV range doesn’t matter - it does matter, and Porsche just spent 100’s of thousands of $$$ proving it does matter and that their product doesn’t quite meet minimum standards in this dimension. I really really hope they have learned a lesson here and that future products do better in this space.

Weight is everything in racing.
Range/Efficiency is everything in the EV world, yes that’s different than the gasoline world, EV’s are different. Efficiency is everything and improved efficiency improves everything!

Saying it doesn’t matter is just ignoring the writing on the wall and assuming things haven’t changed.

 

^ Here is where you are wrong: The "EV world" is constantly evolving at this point. Yes, up until now it has been about range/efficiency in order to prove EVs as a viable alternatives to mainstream ICEs.

Porsche is not playing on that field. It built a performance car that is also an EV. It did not set out to build a one-car solution for the mainstream.

 

At this stage, there is better value in buying a $140k 911 than a $140k taycan! One can hammer their 911 AND daily drive it conservatively for 500km on a 67ltr tank. Good luck hammering a taycan and daily cruising to achieve 201miles/ 321kms range!

However, the rich/ sports stars, for eg, wouldn’t care about range.....would they? Maybe that’s Porsche’s target demographic?