Consumer Reports "The mpg gap"

I had a little trouble understanding this for the longest time, I'm not very good at math, I have a grade 12 barely passing grade in math.
Anyway, that said in Canada and in many Other places we use liters consumed per 100km. I agree that us mpg does confuse as it makes the differences look inflated from what they really are. In your above example 46mpg - 51mpg = 5.1l/100km - 4.6l/100km. Doesn't seem all that much now does it? .5 liters more/less consumed over 100km travelled. Around 75 cents worth of gas at local prices.

 

The average on Fuelly for a 3G Prius is 48.4 MPG. This is about right in between you and Consumer Reports.

On Fuelly for the 2011 3G Prius:
14% of 3G Prius drivers report getting 44 MPG or less.
30% of 3G Prius drivers report getting 46 MPG or less.

Obviously, Consumer reports does more aggressive driving on the Prius - which may be real world driving in bigger cities.

What the EPA doesn't tell you is that they don't test cars on a track. They mount the cars on a dynamometer - a treadmill for cars which is indoors in some warehouse/lab. This means the car is not subject to air drag. Further the cars are given higher octane fuel that what is available to consumers. This is why their MPGs are so optimistic.

 

Car Magazines are for enthusiasts. They like fast and powerful cars. Just look how they focus on sports cars and race cars. Obviously, the drivers are going to drive more aggressively than drivers trying to squeeze the highest MPG from their cars.

Interestingly, Motor Trend's drivers get fuel mileage for the Volkswagen Passat TDI which surpasses its EPA estimates. Obviously, this is one of their favorite cars for daily driving, fun and economy.

 

A Volkswagen Passat TDI did 77.9 MPG while traveling 8122 miles crossing all 48 contiguous U.S. States over 17 days using only 6 Fuel-ups. And it can carry 5 passengers and their luggage with ease, do 0-60 in 8 seconds, and can overtake cars with more ease. So that is pretty close. If you do a lot of highway miles, the Passat is a good choice. It certainly is far more luxurious, quiet and comfortable highway ride than the Prius. Of course for city driving, driving short distances, stop and go driving, the Prius wins in economy. But then, nothing should stop you from buying several cars. A Ferrari does have its uses too.

 

Believe me a grade 12 or grade 13 math in Canada does not equate to a grade 12 math in the USA. I am from just outside of Toronto and that's where my education started at age 3.

Fuel consumed per distance or distance travelled per fuel consumed are just inverted from the same. Do you want the best highscore to be infinite like some oldschool arcade game, or would you rather it be like golf where the lower the number the better. It doesn't really matter and one of them will probably make more sense to someone than the other one. When talking in how much it "costs" to go somewhere having litres/distance makes it really easy because you can just do direct math and multiply by your distance and multiply by how much CDN/litre it costs. Easy peasy. With miles per gallon you need to invert first and people just can't do that very well.

And if you read the whole article you will note that they hypermilled and drove well less than the speed limit. A TDI will not get 77.9mpg on the highway normally. Just like a Prius won't get 80mpg normally. But they both CAN get that if driven smartly.

 

Did you know most canadians and americans have calculators on their phones? Do you think american high schoolers can't use an app on their phones? Maybe those that can't use a smart phone in canada or america will get fooled. Do you think the canadian fleet gets better mpg than the american one?

Gallons per year, or liters per year are the key factor. There is even a little money thing on cost on the sticker of new cars. I don't think the american education system is failing us on mpg.

Now what is failing us is publications like consumer reports like to make news to earn money. They have created tests that do better on ice cars than on hybrids. Since newspapers and magazines love to print stories about hybrids really not getting the mpg on the sticker, CR has been able to have its stories of the prius c etc not getting what the epa gets. The epa test has its flaws, but it was adjusted in 2008 to equalize hybrids. They may need another revision. CR's test seems designed to make hybrids look worse. Just because you don't take certain money, does not mean you are not biased.

Absolutely we can look to the EPA to compare most cars, we can look at clean mpg to fairly show hyper miling comparisons. We can look to consumer reports to get headlines about hybrids and plug-ins getting far under EPA.

 

Being able to use a calculator is not the same as being able to do math. The real world is essentially a "word problem" where you have to pick the variables and make the correct formula. This is very different than telling someone "plug this in to your calculator". And if every time you need to do a basic comparison you need a calculator you are less likely to understand what is going on.

I didn't say the canadian fleet gets better mpg. But Canada is one of the top scoring countries in the world in education lumped in Finland and Korea. Even if you compare scores only within similar socioeconomic classes, the US scores substantially lower than most of the rest of the industrialized world and always less than Canada. Criticism should be taken as a reason to do better and achieve the #1 position. If you blind yourself to the facts and just continue to declare you are #1, you are laughed at on the global stage for good reason. Admit there are failings, fix it, and win. Every country even those at the bottom should be trying.

 

Lol, I love it Bob. I know you have a scientific heart, so would you consider driving it like Jeremy Clarkson on a mission to prove the Prius is an abomination and see just how bad of fuel economy on the same loop you can manage.

 

Since I have taught college level courses, I was not equating calculator to math. I was saying that mpg doesn't require a 12th grade math education, it just takes a calculator. Miles traveled /gallons used. Not too tough, I did it on family trips when I was quite young. For gallons per year miles per year /mpg. No reason to spout off on why education is so superior in canada. If you understood the calculation with your fancy canadian education then you would know that americans are quite able to do these simple calculations. Very few can do it without a calculator.

Well bully for you. You have brought something quite off topic to criticize the american education system. bravo. How many canadian nobel prize winners are there? Oh right, that is totally off topic. If this was a forum on math education it would be constructive, on a topic of CRs mpg tests being far off of the EPA, it seems like you are trying way to hard to bring your america sucks attitude to the forefront.

I have a friend who is a professor of math education, and she regularly updates me with the research. I have never heard that there was a problem with students doing mpg. The US education system could defintely use improvement, but this has absolutely nothing to do with not being able to plug miles and gallons and mpg into calculators. Kids are quite good at that.

 

The VW website stats don't reflect what you're saying. The best mpg figures for a Euro Passat Bluemotion with the 1.6 engine is 78 mpg but with a combined of 65 mpg. It has a 1.6 engine with a manual gearbox and does 0-60 in 12.5 seconds.

I also can't find the NOx emission limits quoted on their website. Funny that.

Overview : Engines : Which model : Passat : New : Volkswagen UK

Diesels are getting nearer hybrids if you do lots of highway driving and they'd probably be a comfortable drive. But most traffic in Europe is city driving and even with that crude stop start system VW employ, the fuel economy would be crap. Especially with your a/c on.

Horses for courses but you live in America and don't have to breath the diesel fumed air our cities have. The emission stats for Euro 5 petrol v diesel are scary reading. Often manufacturers will hide the ones they don't want you to read.

Here is an emission comparison between the best petrol hybrid, petrol and diesel figures of the brand new Toyota Auris;

Hybrid CO mg/km 124.3
Petrol CO mg/km 214.9
Diesel CO mg/km 195.6

Hybrid NOx mg/km 5.7
Petrol NOx mg/km 12.7 (worst) or 7.1 (best)
Diesel NOx mg/km 112.7 (thats 112.7 not 11.2!)

Hybrid CO2 mg/km 82-92
Petrol CO2 mg/km 110-186
Diesel CO2 mg/km 90-121

So maybe US diesels have much cleaner emissions at a greater cost but breath the air in our cities and you'll grow to hold diesel in a different light.

 

Bob, wasn't it years ago that the whole CR unfair / irrational issue came up ... as well as the good sense of dropping subscriptions? It was one of my motivators. Seems like it was at least a half decade ago you brought this glaring issue up. Maybe it was me. I duno ... maybe old age ... but yea, I dumped CR way back due to these kinds of inconsistencies. I tried searching old threads ... but after the software migration ... it's hard to do.

Some of us are old enough to barely remember the slide rule ... even my better half, four years younger, and a child of the calculator age remembers the slide rule. But her dad is a retired EE - and insisted she learn such antiquities ...
.

 

My government and bankaccount do.
(2500$/year in roadtax for the first car, 0$ for the Prius (but 800$ as of next year as the incentive runs out)).

 

Then perhaps you can explain why it is so common to hear that off by 1 mpg in a big truck compared to EPA is fine, but off by 4 mpg compared to EPA for a Prius is not.

Feel free to use your calculator.

Seems to me that if a person cannot estimate the answer to this question in their head, a calculator is not going to help.

 

Car Magazine/Enthusiast Test Drives are focused on demonstrating a vehicle's performance characteristics not fuel efficiency. Test circuits are often very twisty and hilly roadways combined with a flat straightway. The testing objective for curvy road secgments is to determine fast a vehicle can take a curve before centrifugal forces makes the vehicle unstable and or the vehicle's on-board-computer automatically brakes/slows down the vehicle so that all four tires remain on the road. The hilly terrain is to see how much power is available to go up a very steep uphill climb. The straightway is used to test the vehicle's acceleration, top speed, and braking performance. All in all fuel efficiency for vehicles with power to spare like a Corvette should be about the same - but fuel efficient vehicles with very limited power in reserve will normally run inefficiently when pushed hard on the track of this type and their fuel efficiency will often be poor or uninspiring.

 

The Volkswagen Passat TDI is a fine car. However, the VW Passat TDI that achieved 77.9 MPG over a 8122 miles marathon that crossed all 48 contiguous U.S. States over 17 days using only 6 Fuel-ups was not driven by just any driver and it wasn't driven in the conventional way most people think of as driving. The driver team was composed of two elite Hypermiling experts - Wayne Gerdes and Bob Winger both who are dedicated hypermilers with a proven marathon track record. This hypermiling marathon run was documented in a Cleanmpg.com blog/forum. Each day, the hypermiling driving team started at about 9am and finish their run for the day sometime after midnight (doing an average of 480 miles in about +13 hours of driving per day) - with the overall average speed being closer to 35 mph . Gerdes says that his average speed on certain road segments was sometime as low as 25 mph. Gerdes and Winger are experts at using hypermiling techniques like NICE and DWL which most drivers can't do. In addition, Gerdes and Winger were using a Scangauge2 - an very uncommon fuel efficiency monitor/tool that provide more information than the VW Passat TDI's on board computer. There is no way the average driver is going to get that kind of result. Heck, even a *skilled* hypermiler like me would have trouble duplicating that kind of result by myself. One reason a driving team was used is because that allows the drivers to share the workload - so a driver only has to be behind the wheel for 6 to 8 hours per day. For most drivers, driving longer than 12 hours per day is not sustainable.

 

BBC Top Gear's Jeremy Clarkson does not have a scientific heart like Bob Wilson- Jeremy Clarkson is a TV syndicated circus clown for the car set. Clarkson can be fun to watch (because he is often outrageous and very passionate ) but it is a mistake to take him at face value. Bob might be intense at times but he is pretty up front and matter of fact kind of guy. Bob has been upset with CR for a while - however, I no longer subscribe to CR so I guess I am sort of less upset.

Top Gear doesn't disclose its *testing* methodology and Clarkson has a history of rigging results
for alternative energy vehicles so they will do poorly. BBC Top Gear's road test for the Tesla Roadster and the Nissan Leaf were both rigged and the BBC Top Gear reported results were fabricated. Unlike Tesla - Nissan caught BBC Top Gear's faking test results because of the Nissan Leaf's on-board real time satellite link downloaded Top Gear's every move.

However, of all the alternative energy vehicles, Clarkson hates the Prius the most.
Of all the alternative energy vehicles on BBC Top Gear , the Prius is the only one that Clarkson has ever used explosives to blow up,,, yeah - he hates the Prius that much...

 

Actually, they do tell you our their fueleconomy.gov site. It's where the OP pulled the graph for one of their tests from.

Running on a dynamomter eliminates many of the variables the CR's and others 'real world' tests that makes essentially useless for comparisons between cars. Indoors means not being subject to varying temperatures and crosswinds at the least.

Air drag is factored into the EPA test. A roll down of the car is performed before hand. From this air resistance, tire friction, and drivetrain friction can be determined in order to set the resistance of the dynamometer rollers for the car's test. The test gasoline formula was set back when the EPA was first required to test vehicle emissions. Which is the primary purpose of the test. Measuring a cars fuel economy through it was realized afterwards. This was before the ethanol requirement, and using a high octane meant not having two different formulas for testing low and high compression engine cars. It's another way of controlling variables in the test.

How Vehicles Are Tested

 

At that average speed a Prius hits ~ 100 mpg without trying.