Consumer Reports "The mpg gap"

Fuelly does give a recap on how well one can do with better mpg's, and for the Prius it does not make sense to chase - see attached - this was after a 567 mile tank.

Not sure how to address why here in the US we don't use a gallon/100 mile model - other than to get us forget just how much our driving here in the US is costing us. My lifetime Fuelly is showing that I am getting 1.9g/100 miles. With my 100 mile weekly commute,I know easily that it costs me between $7 and $8 a week to just get to work based on $3.50 to $4 a gallon. The only simpler way is for mpg ratings to show actual $/100 miles or km...

My fiancé loves it when we take and drive one or the other in to work our jobs are just 10 miles away from home. His car is a Yaris - so based on Fuelly the cost is between $9.50 to $11 based on 100 miles. While $2.50 to $3 per 100 miles does not sound great based on our miles driven per a year - we are learning that it adds up.... We are trying to see how we can make things work between our jobs in order to commute together.

In the end I believe that making car owners aware of costs per 100 km or mile will have a positive effect....

 

I still subscribe to CR but I too sense an issue on auto reporting. For me, I originally wrote CR and EPA a letter/email (neither responded) re: MPGe as a misleading metric. CR kept saying 100 MPGe means Plug_ins sip very little fuel/energy, I was trying to say no, they use lot's of energy, 100 MPGe just means sipping less gasoline. The thing is, it's Consumer Reports...I am (mistakenly?) expecting impartial assessment getting to the honest truth of the matter, and not USA-centric politically correct attitude.

 

With all the stops to document every detail and border crossing I'm sure their average speed took a big hit. 25-35mph is probably well below the minimum speeds on those roads. Their road speed would probably be nowhere near that low.

 

Historical reasons are normally the best guess for why we measure a certain way, and it is true here. When the car came out what was important? That you had enough gas to get to your destination. If you got 13-20 mpg in your model t, and wanted to go 150 miles you might have to carry extra gas if there wasn't a station. Prohibition stopped you from just stopping and picking up some ethanol to pour in the tank. In Europe they picked a different convention. Neither is better than the other, unless you can't do division. Remember YMWV (your millage will vary). Most people that care have an idea of how much gas costs them a month.

We have a computer in our car and can switch from miles to km and mpg to whatever the europeans use. Perhaps if it is important you can write to toyota to get it on the trip computer. If you want to compute g/100 miles from the window sticker, just plug 100/mpg into a calculator. No one is forcing anyone to use miles or km or any other convention.

The issue here is whether the CR test is misleading. I am with bob that it is when comparing hybrids to ice cars.

 

The CR test loop is through a two lane country winding road with rolling hills to simulate city driving.
The winding road portion requires braking and acceleration, all this hurts mpg. They do not drive in actual city traffic because the condition cannot be repeated for different tests. Their test loop is actual quite repeatable as mentioned before they require driving in predetermined speed and to sit in the car for fix amount of idle time.
It is a fair test for car to car comparison.

 

Depends how you define fair. Clearly the numbers they got here show that their test is much better for more powerful vehicles.

 

I only saw it in Youtube. May be you can figure out where it is located.
This is one of them.

 

Consumer Reports Auto Test Track (Bing Maps) - Virtual Globetrotting


I am not sure how the map will help you though. The question is really are the tests valid. Does consumer reports test more accurately what a typical driver will see. For the city portion, with hybrids it is likely that the EPA test underestimates the cold start penalty of the city portion. For the hwy portion the low speeds on the EPA test help less aerodynamic cars. For a car like the prius it likely is a wash, overestimating city, under estimating highway. The tests can be improved.

We don't really have much of an idea what is going on in the consumer reports city test, as they have not specified speed, distance, number of stops per mile, etc. It seems to drastically underestimate city mileage. Similarly their highway test is long at a constant speed, that is quite different from user experiences except on long trips going much slower than we do in my state. It likely over estimates mileage. Since the CR seem to penalize hybrids through their methodology I find it hard to believe we should choose their numbers over the EPA. Perhaps you can add the hwy portion to the epa information. The city test? I don't think hybrid drivers drive that way.

 

Only as long as you believe differences in air temperatures, prevailing winds, and the difference between summer and winter blend gasoline with varying amounts of ethanol have no bearing on vehicle fuel economy.

 

They have been testing car for many years or hundreds of car, they should have enough data to make corrections to these variables.

 

Any guess at validity if a chevy malibu eco gets its EPA milage on the CR tests, but a prius C gets 14% worse mileage on the CR test?

Make & model CR overall mpg EPA combined mpg Difference
Ford C-Max SE 37 47 10
Ford Fusion Hybrid SE 39 47 8
Toyota Prius C Two 43 50 7
Toyota Prius 44 50 6
Honda Civic Hybrid 40 44 4
Infiniti M35h 25 29 4
Lexus ES 300h 36 40 4
Buick LaCrosse (4-cyl., eAssist) 26 29 3
Honda Insight EX 38 41 3
Hyundai Sonata Hybrid 33 36 3
Lexus RX 450h 26 29 3
Lexus CT 200h 40 42 2
Toyota Camry Hybrid XLE 38 40 2
Chevrolet Tahoe Hybrid 19 20 1
Toyota Highlander Hybrid 27 28 1
Toyota Prius V Three 41 42 1
Chevrolet Malibu Eco 29 29 0
Honda CR-Z EX (manual) 35 34 -1

 

What I meant, was Bob drove to prove the Prius can do this loop at 99.9mpg. Cherry picking results, similar to what CR does. It is great though because more of these sorts of datum points might break the prevailing myth amongst people that a N mpg car gets N miles per gallon no matter what conditions, speed, driver, or anything else.

I suggest that Bob drives the Prius around the same loop with 0 regard for fuel economy. Pretend you are Jeremy and on a mission to prove to the world that the Prius is the worst machine in the world. What sort of tricks would you pull? Drive with the e-brake slightly on, AC on max while the defrosters are on start with a 2-bar SOC, brake hard and often, accelerate pedal to the metal at every opportunity, lower the tire pressure to 30psi, that sort of thing.

Then we can show the loop when driven by a Bob-ite gets 99.9mpg. The same loop driven by a Clarkson-ite gets ### mpg. My guess is that it will be closer to 30-35 mpg.

 

Seriously? Just because the test is the same for all cars does not mean it is a fair test. What kind of technology is in use does matter. What if I defined a test as driving a few miles, then sitting and idling for 15 minutes, then driving another 2 miles and idling for 15 minutes, etc. Virtually all ICE cars would show horrible results and all hybrids would do great. I wouldn't call this a fair test because it doesn't mimic what average drivers actually do.

As it is, their test (it seems) always tends to accelerate hard and brake hard and not coast to stops, for example.

Mike

 

They do tell you that they use a dynamometer.
And they do account for air drag by mathematically adjusting the results.
This is actually MORE accurate in that they have no cross winds, no tail winds, no head winds which happen in real driving without any tester control...every car only gets the penalty of speed induced head winds based on the Cd for the car under test.

I suppose one could argue that different cars have different reactions to random cross winds and that should be taken into account since real world driving has these effects.

Mike

 

Nah.

The dyno and roll down method to calculate rolling resistance is fine; the problem is protocol.

• Should the test tease out regen ?
• Should the test tease out coasting ?
• How about partial power penalty differences between cars ?
• Should the highway test be performed at 65 mph ? 75 mph ? 85 mph ? The G2 Prius transmission becomes increasingly inefficient at speeds over 75ish mph. Should the test expose that weakness ?

I routinely hit around 70 mpg in my Prius vagon in city driving. Part of it is not driving in a congested city with aggressive drivers; the other part is knowing the strengths and weaknesses of my car and driving accordingly.

Should the test assume least common denominator -- that every driver is an idiot who has either the brake or the fuel pedal mashed to the floor ? CR seems to think so.

I would like to see
City(moron):
City(smart driver):

Or even better, let the drivers drive a simulated course with pseudo- random traffic, any way they want so long as they finish the course within a prescribed time, drive legally and avoid certain proscribed behaviors. Report 3 time trials. We will give up exact reproducibility, but have an informative test instead that says a lot about the car AND the driver.

 

+1

I wouldn't say Jihad. I would say fake news war against hybrids otherwise how do you explain this
Fuel Economy - Consumer Reports



That leads to anti-hybrid editorials like this

How many miles per gallon does your Prius really get? - The Denver Post\

Unfortunately for us, consumer reports isn't really mimicking real world conditions. The EPA tests can be helped, but this analysis by car and driver would have even more problems with consumer reports then the EPA

Why Is the EPA So Bad at Estimating Hybrid Fuel Economy? – Feature – Car and Driver

They advocate forcing hybrids to test all 5 cycles, hot and cold, and raising the speed of the highway test. Consumer reports testing does not really address the problems with epa testing at all, they simply add their owned biased tests. How many of us drive on the highway every day at 65mph. Many of us have traffic and slow down and speed up, or go much faster on trips. We deal with hot and cold weather. I don't know anyone whose city mileage in a prius is as bad as Consumer reports got on their test. Misrepresenting any set of flawed tests as accurate seems to be getting consumer reports lots of press. Unfortunately it is really a poor anti-hybrid agenda.

A little detail of their city test

Every turbo owner knows stomping on the gas will lead to worse mpg. If they are driving for economy they will accelerate like hybrid drivers slowly. 5%of the time they will stomp on the gas for fun, and that won't ruin gallons per year.