Featured Tesla has been cheating EPA on mpge and range numbers

If Tesla actually cheated, they should be punished.
All you have shown is that the EPA test is different than the Edmunds test.
The EPA allows two methods, Tesla chose the second. That isn’t cheating.

I’m all for the EPA testing Tesla vehicles to insure the numbers are correct.

BTW, I beat the EPA numbers with my LR RWD Model 3

 

The EPA tests were never designed for predicting fuel efficiency on the roads. They designed for ensuring cars were complying with emission regulations. Fuel use was just an additional data point. If it was left at that, the Prius would have a window sticker rating around 80mpg. From the beginning, fudge factors were added to the results the public saw. Currently, the adjustments result in numbers closer to real world user results than any other official test in the world.

The EPA posted numbers are an average from multiple test runs. These magazine tests are just run once.

The law only forbids manufacturers from posting numbers better than the test. They are free to post worse. Toyota could give the Prius a 50mpg or even 20mpg rating on the window sticker.

Tesla isn't overestimating. They are using the optional tests to get more accurate adjustment factors, and publishing ranges based the battery's full capacity, including the portion after the distance gauge reaches zero. This is legal. Just like it is legal for Toyota to slightly underestimate the results for the window sticker.

The Model 3 SR+ over estimated its range by 7.2% from the Edmunds test. It under reported its efficiency by 4.2%. While not reaching their EPA ranges on the Edmunds test, all but one of them matched or bested their EPA efficiency rating. The bZ4X did the worst in terms of Edmunds to EPA efficiency.

If you are comparing different models, you want the lack of variables in a lab test. The Edmunds tests were run with a 23 degree F difference in temperature, with unknown differences in wind patterns, weather, traffic conditions, and driver style. CR's results are real world with a standardized approach, and they reported 35mpg for a gen 2 or 3 Prius.

 

Do remember that when hybrids first came out, their EPA scores were quite high, well above what most ordinary drivers were getting. After some years, the EPA changed the scoring system to make it more realistic for hybrids too.

Perhaps, if the EPA receives a similar volume of complaints on EV range scores, they'll do the same for EVs?

Remember also that "ordinary driver" is a moving target, as speed limits and average speeds have continually increased since the National 55 MPH speed ended, and drivers get more aggressive, gradually so for a long time but sharply so since the start of the Pandemic. All these things reduce MPG, MPGe, and range.

 

In my experience, one day I can get 120mpg out of my Avalon, and another day I barely get 15mpg. The same in the Leaf. One day I went 115 miles on a single charge and didn't even start out with 100%. Another day it died at 30 miles starting with 100%.

 

I think you are confusing an inaccurate test with cheating. What vw did with diesels was cheating, they used software to detect emissions and mileage tests and changed the behavior to do well on each, performing much worse without that software (pollution was much higher in real world). The EPA test appears much more accurate than the WLTP which is more accurate than the older NEDC and Japanese 10-15 tests. EPA 2 cycle was based on how people drove in LA in the 1940s. They added 3 tests (cold weather, warm weather, highway speeds) to try to correct and added fudge factors, but a new group of tests would be better, if it showed how people really drive.

I don't think that Edmunds test is that good either. It is not repeatable because it doesn't apply the same conditions. It is mainly driving in LA traffic which is highly variable. Temperature range on cars is between 55 and 77. Nowhere do they test a car in very cold or hot conditions. I guess if you live in 2022 LA it may be a good test.

The important range component is highway range. Car and Driver does a 75 mph test, insideEVs does a 70 mph test. Those combined with the epa information will give people a good understanding. When I am taking a lot of short trips in 100 degree heat, my consumption is more. Why? Well I turn the air on before I get in my car. That takes energy. I park it in sentry mode that monitors its surroundings. Do I care that it takes more doing those things? No range doesn't matter most days, especially ones where I am driving less than 40 miles.

 

The problem with tests and real world scenarios is they aren't ever the exact same.

I wish, before buying my next vehicle, I could have the chance to rent one, put tire chains on it, and drive it over the worst possible route in some of the worst weather just to see how it does in a worst case scenario before buying one. That, or hear experiences from people who have driven in such circumstances. But usually people that buy the kinds of vehicles I want to buy don't drive them in the circumstances I live in and they end up just saying things that may be true, but don't have any real world "testing" behind them to be sure.

 

Edmunds tried for a 60% city to 40% highway road mix. The EPA range is based on 55% to 45%. Most of the Teslas were with 10% of their EPA range on the Edmunds test, as were many of the others. Look on Fuelly user results, many are within 10% of the EPA mpg rating, better and worse. The EPA tests look to be doing fine for their purpose.

For the EVs getting much better than EPA, there is a couple of things to consider. One is that the manufacturers can choose to use a mathematical model to determine the window sticker adjustment. This is for any car, and is to allow the manufacturer save some cost over running three more test cycles. It results in a larger adjustment down. So EVs get an official range shorter than real world. Compared other tests used by other countries that give EV's ranges longer than what they can achieve, this is the better result for the consumer.

Another is that the test cycles are ones developed for 1950's ICE cars.Some things that improve efficiency in the real world don't come into effect during the test. The Taycan never made use of its more efficient cruise gear during the test for example. Changing the test cycles requires an act of Congress.

As for your Prius Prime Model 3 comparison, the engine in the PP is more efficient than the one used in the first Prius. Motor efficiency varies like it does for engines. Tesla has some of the most efficient motors used in a car. I think only Lucid is better. Then being a PHEV, the PP has some loses in EV mode from spinning things that are only needed when the engine is running. That's why the Model 3 can match or beat the PP in EPA ratings.

 

Anyone else feel like starting up another Myth Busters show?

Lots of people think weight is a number one factor of energy loss. But especially with much more efficient modern regenerative braking, weight isn't a huge factor. Most of the energy being lost going down the highway is still to pushing around air, even in a Prius Prime or a Tesla. I wish more car companies would take cues from the Aptera design. Also the Prius Prime and the Tesla 3 aren't that different in weight either. A base PP is only about 280lbs lighter than a base M3. And even though a fully loaded M3 is almost 900lbs more than a fully loaded PP. What mainly matter are the shape and cross sectional size. The PP is taller but the M3 is wider and both are pretty close in shape, so I don't really know how well their CdA's compare.

 

How are you figuring that?

The EPA mi/kWh for the Model 3 SR+ is 4.17. Edmunds got 4.35, and Bob 4.42.

For the Prius Prime, the EPA is 4.0, and you get 5.6.

You can compare the EPA of the two models. You can compare the EPA to what users got of with the model.

You can't compare what users get in different models. There is too many variables between the route and driver style.

You would very likely get the same or better than what you get in the PP if driving the Model 3 over the same conditions.

The Cd of the PP is 0.25, and the Model 3 is 0.21. The frontal area, not counting mirrors, of the Model 3 is about 1 square foot larger. With the Cd difference, it ends up with the better CdA; 6.031 to 6.965.

 

You mean rolling resistance. Yes, it increases rolling resistance. But at highway speeds the air drag is greater than the rolling resistance. A 280lb difference isn't going to make a huge change in rolling resistance either. Although I have to admit that these are vehicles that are heavy enough and aerodynamic enough that the rolling resistance is creeping up on the aerodynamic drag. But going down a highway at +60mpg and up, adding 500lbs or more isn't going to have that great of an effect.

 

The best Edmunds tests were the old "Smack Down" series:

• Three or more press cars over three days with drivers swapping during each day
• State roads San Diego to Las Vegas
• City driving in Las Vegas
• Interstate driving Las Vegas to San Diego

Three days with each driver swapping cars within each day. Then they collaborated on the story to rate the cars. Same route and weather, entirely credible, relative performance.

Bob Wilson

 

Not for everyone.

You are assuming all these car companies are publishing the maximum range the law allows, when they are free to publish something lower. Some of them don't include the emergency buffer of energy still available after the range display reads zero miles left. Tesla does, which lines up with the practice of published ranges for ICE cars being with running the tank dry. Edmunds did another test where they did run some EVs until the car refused to move. The Model 3 LR went 22 miles past zero at 65mph, which would put its range from the other test over the EPA range. The three Teslas in that test all had more emergency range than the ID.4 and Mach-E. They were all done on the same day.

My last tank over my normal daily route was 37mpg in a 29 combined mpg rated car. I'm pretty confident I could beat the EPA in any of these plug ins.

 

I'm having a hard time finding numbers, but this is what I came up with:
Tesla Model 3 2.22m^2 .23Cd curb 3,648lbs
Toyota Prius Prime 2.40m^2 .24Cd curb 3,365lbs
Assuming average atmospheric conditions at sea level, 0.008 coefficient of rolling resistance and 500lb total payload:

At a certain point any vehicle will be using more energy to push air than to roll.
The Tesla will hit that mark at 49mph, and the Prius Prime at 45mph.

At 75mph the Tesla will be using 70.4% of it's 16.7kW of total power at the wheels to counteract air drag, and the Prius 74.3% of its 17.9kW.

At the lightest base option both use the same amount of power at 40mph. Above that the Telsa uses less, and below the Prius.

Those are base vehicles, now let's do the same calculations with the heaviest options:
Tesla Model 3 4,072lbs
Prius Prime 3,375lbs

The Telsa starts using more power to combat air drag at 52mph and the Prius still at 45mpg.

At 75mph the Tesla will be using 68.4% of it's 17.2kW of total power at the wheels to counteract air drag, and the Prius 74.2% of its 17.9kW.

At the heaviest option both use the same amount of power at 55mph. Above that the Telsa uses less, and below the Prius.

So yes, increasing the weight of the Tesla to the heaviest option (+602lbs) means it'll use about 500W (3%) more of power to travel at 75mph than its lightest option. The Prius, because of it's taller stance and slightly less aerodynamic shape, actually needs more power at the wheels to maintain its speed at highway speeds than even the heaviest Tesla Model 3, at least on paper. It would seem the Prius would have to have slightly more efficient motors (or something else in the test) to make up for the difference. But the difference is so small that either could need a very small bit more power than the other at any given speed.

Let me know if any of my numbers are wrong. I couldn't find any official data, but this seems to be as close as I could find.

Some references:
Tesla Model 3 - Wikipedia
Toyota Prius Weight (autopadre.com)
Solved 1. Data for the Tesla Model 3 shown in figure 1 are | Chegg.com
toyota prius drag coefficient (2022) (ngontinh24.com)
Aerodynamic & rolling resistance, power & MPG calculator - EcoModder.com

As I was saying before, it's mainly the shape (air drag) not the weight, that will affect the fuel or electric mileage the most. Yes, a Tesla Model 3 can weigh some 700lbs more than a Prius Prime, but that's still not going to be a major factor. It's the air drag that's the main problem, at least at speeds of over 50 some mph or so.

 

In post #37, Isaac Zachary posted a nice analysis of the aerodynamics VS mass. What I think that he left out was that the rolling resistance is additive to the cost of drag, no matter what speed you are traveling. This makes a difference because a brick shaped car with soft tires will have horrendous drag at 70 MPH but it will ALSO have terrible losses due to high rolling resistance regardless of the vehicle speed. The same goes for overcoming inertia. A teardrop shaped car will have a lot less drag than most designs, but it will still have to overcome inertia as it accelerates and it will have losses due to rolling resistance whether traveling at 30 MPH or 70.