Featured Tesla has been cheating EPA on mpge and range numbers

Um no. The plot shows the exact opposite.

F=A * V^2 * Cd * D

Look at the plot.

 

What are you saying? The rolling resistance magically drops as it speeds up? Explain why the two curves start separated and then come close if it's not that the Model 3 has a better CdA than the Prius? What on Earth could possibly cause that?

The slight increase at much higher speeds could be motor drag related, since there is no other explanation. In a vacuum, the rolling resistance would make one flat line along the bottom. Add aerodynamic drag, and the curve will increase steeply or gradually, not gradually then steeply or visa-versa. Air drag is a multiple of V^2, velocity squared. It's always velocity squared, not velocity cubed or velocity to the power of 1.9. The curves are not a perfect exponent of 2 because of mechanical drag that has it's own exponents.

I bet if you got rid of the motor and drive lines in both and just put weights in there to compensate for the missing motors and stuff then the Tesla's line would cross the Prius' due to its better CdA.

 

So, no contribution from the larger battery, able to accept a somewhat higher rate of regeneration?

No contribution from its higher ICE-Off threshold speed (about 80-ish mph, vs 60 mph on regular Prius), allowing more efficient no-ICE-drag glides to the very highest speed in EPA test cycles?

No improvements borrowed from the higher MPG Prius ECO?

No contribution from any additional design improvements from the one year extra wait, Model Year 2016 to 2017?



P.S. See also rear wiper delete.
P.P.S. The regular Prius mix also includes a certain fraction with lower-MPG 17" wheels, not available for Prime and Eco.

 

The Prime has the same Cd as the Prius. The rear window shape improves it, but the front end design increased it, leaving it at the same spot. Toyota said so during the Prime's release.

 

This is definitely not the case. You make the small increase at the end look like a big huge CdA difference in favor of the PP when it's so close there's no way of proving that. Yet the huge change at low speeds is wider tires or "some other known factor"?? Sorry, I'm not buying that.

The PP has a worse CdA until someone shows the numbers proving that otherwise.

 

It seems that this whole thread takes a different turn if it were titled "Tesla has leveraged loopholes in the EPA MPGe and Range tests to look better than than what they deliver in real life.

It's not cheating. It's not even really dishonest. It could even be considered ethical.

But I would not trust a company that has to game the system in order to look better than the competition. VW, Tesla and Hyundai come to mind.

 

Nope. That's not math.

The Model 3 has a CdA of 0.511 m^2
The Prius Prime has a CdA of 0.576 m^2

Prove me wrong other than a line that's a couple of pounds in favor of a car at 80mpg that started with about 10lbs of difference at 20mph.

Do the math. Show me your equations and stop it with the "unknown factors" that only work in your favor on the premise of your intuition.

We are talking about drag here, right? What kind of "unknown factor" makes drag work in the negative sense? If Telsa has such an "unknown factor" they must have discovered the discovery of the century. Pretty soon they will have perpetual motion vehicles that don't even need to use any sort of fuel or electricity as this "unknown factor" makes their cars act like rolling resistance and air drag mysteriously start pushing the vehicle instead of slowing it down as the it reaches a certain speed.

If that's all you got, that since a Tesla needs two pounds more force to go 80mph than a Prius so because of that Tesla is lying and cheating and we need to protest around Tesla factories and burn them down and hang Elon Musk because they use some mysterious anti-force aka "unknown factor" that helps push their cars down the road the faster they go to make it look like they have a better CdA when they really don't, well that's it. I can't help any more. Sorry. The numbers, math and chart just do not uphold your claims. I'm really sorry, but no. Just no. It doesn't work. Nice try, but it doesn't work. Friction, without a way to decouple it, always increases.

Well, now that I think about it, maybe the angle of the Model 3 changes... Never mind. Maybe, but it seems like a long shot that the Model 3 has a wrong angle at speeds below and above 55mph due to the changes in down force on the front and rear. But that's all i could think of that might possibly support your claim. I still don't see it, and that would still prove the M3 has a lower CdA anyway. It makes more sense to me that if the numbers on the web say the M3 has a lower CdA, and it looks like it does until 55mph, and after that it looks like it has nearly the same as the PP, then it makes more sense to me that there is extra drag above 55mph, not negative drag up until 55mph.

And here's the real kicker. If we could take rolling resistance out of the equation, then the lines would start at 0 drag at 0mph, and be almost 0 at 20mph. If we put those two lines to start out at 0 at 0mph the Tesla would end up about 6 or 7lbs less than the PP at 80mph. Why? Because rolling resistance doesn't change with speed. If we took air drag out of the graph, you'd have two horizontal lines. The PP would be at about 32lbs from 20mph to 80mph, and the M3 would be at about 40lbs from 20mph to 80mph.

Rolling resistance is the same force, regardless of speed. Air (or any fluid) drag if a force that increases exponentially with speed. Got it?

 

But they do!

His graph shows that at 20mph there's about 32lbs of RR for the PP, and about 40lbs of RR for the M2. So at 80mph the PP has about 130lbs of total drag force, which if we subract the RR (130 - 32 = ?) we get 98lbs of air drag. And for the M2 it's around 40lbs of RR at 20mph, but about 132lbs total drag force, which if we subtract 40lbs... what do we get?? More CdA?? No! Sorry! It's (132 - 40 = ?) 92lbs.

So the graph clearly shows the M3 has about 6 fewer lbs of air drag force at 80mph than the PP. So yes, it is where it's most pronounced. But you have to keep in mind there is still rolling resistance. If the M3 has higher rolling resistance at any speed, then obviously it has a lower CdA.

And again, lubricant is a fluid. Fluid dynamics are fluid dynamics. Fluid dynamics is speed squared.

And we're still going at this over a 2lb difference at 80mph!?

 

I also went with higher wear rating. So I used the Bridgestone ECOPIA tires which have performed as expected.

I use the Bridgestone load specs to make sure. I run at max sidewall pressure for the weight capacity, handling, and long life.

Given the OEM tires are the same as the heavier, 75 kWh vs 55 kWh, Model 3, this was an improvement … called tuning. Lower sprung weight, lower moment of inertia, My benchmarks showed lower kWh up to 45 mph. Lack of aero wheel covers showed a little worse aero drag at highway speeds. The vast majority of my miles are slower urban speeds.

Bob Wilson

 

Yep, it is the unfounded accusation of cheating by Tesla that started this. Then the Prius Prime is being used as proof of this. Toyota tends to under report fuel efficiency and range, so we aren't at 100% like to like.

All Tesla is doing for range is what has always been done for other cars' tank range; posting a number that counts every bit of energy the car could carry. They also choose to use the extended EPA tests to get a more accurate result for the window sticker. Go through the OP article's tables, and you'll see some of the Tesla's exceeded their EPA fuel economy rating despite not reaching the EPA range. You'll also see they missed the EPA range by 8 to 11 miles, which more than likely would have been reached if the cars had been driven until the battery was totally flat.

The others are choosing the cheaper EPA method that results in conservative numbers that can be used on the window, or are purposely under reporting to manage customer expectations

Hyundai made mistakes over confusion with the testing rules. After fining them heavily, the EPA went and clarified those rules.

Ford was knowingly abusing loopholes, but are an American company.

VW purposely broke the law to not just pass the tests, but get an unfair advantage in the market in other companies were unable to even field competition. I'm boycotting even their EVs.

And you are yet to supply numbers from another source that contradict them.

 

Since October 2005 and our first Prius, "unfounded accusations" has been the rule. Examples include: quiet Prius running down the blind, pedestrians, and cyclists; "Dust to Dust" claim Hummer is better than Prius, and; unintended accelerations. It had never occurred to me that a Prius owner would adopt similar propagandists practices starting with inaccurate titles to new threads. Regardless, it is also an opportunity to reply with the the facts and data. As Lincoln said:

You can fool all the people some of the time
and some of the people all the time,
but you cannot fool all the people all the time.​

In our case, the 2014 BMW i3-REx with 72 mi EV range was used more than our 25 mi 2017 Prius Prime. The BMW worked in true EV mode while the Prime control laws and short EV range meant it had to burn more gasoline. So the Prius Prime became expensive driveway sheet metal art. Trading the Prius Prime in for a Tesla Model 3 Standard Range Plus made more economic sense than losing the BMW i3-REx. But we are not alone.

Source: https://electrek.co/2018/08/01/tesla-model-3-top-5-trade-in-cars/

During the investor conference call today, CEO Elon Musk revealed the top five trade-in cars:

• Toyota Prius
• BMW 3-Series
• Honda Accord
• Honda Civic
• Nissan Leaf

It’s important to note that Tesla specified that it’s the top 5 “non-Tesla” trade-in cars, which would indicate that a Tesla vehicle would actually be in the top 5 otherwise.​

Bob Wilson

 

And how many angels fit on a pin is what this discussion has evolved into for me. The source for the motive power and the type and location of the emissions produced by a plug-in hybrid and a EV differ and that matters more to me than a bunch of figures differing by such small amounts.

 

But the Telsa needs over a 100hp to go 80mph, 102hp to be exact, yet the Prius Prime needs much less than 100hp at only 99hp to go the same speed. That's like a whole 3% difference at 80mph. Sorry for the sarcasm. But it is indeed a small amount.

 

My first chart compared models that I have and had owned. This chart is from 2021, the last year all three models were for sale:

Tesla makes improvements on the fly. So the low-speed performance has improved as did the high speed performance. Again, the best tuning strategy for the Tesla Model 3 Standard Range Plus is to reduce tire rolling drag which I did.

Bob Wilson

ps. For the difference:

 

Compared to the last chart it looks like the driver didn't stick his elbow out the window as far this time.