Cars.com's True Mileage Index Tells it Like it Is

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There’s one glaring problem with how the government comes up with its fuel economy rating system known as CAFE: None of the numbers or calculations have anything to do with the EPA-rated mileage you find on a car’s window sticker, also determined by the government.

Cars.com took on the massive undertaking of using EPA figures (which have recently been revised to be more accurate) along with a number of other factors — including sales, engine and transmission options and more — to come up with a new list: True Mileage Index. 

We rank the major automakers on what their actual fleets really return in terms of mpg. The numbers may be shocking; if automakers advertised them, few people would think any of them are really fuel-efficient.

If we want to get serious about fuel economy and holding automakers accountable, the public should be armed with figures that are based in some form of reality. Let us know what you think in the comments below.

The Cars.com True Mileage Index

By David Thomas | August 1, 2008 | Comments (18)

Comments 

I find it amazing that Lexus has better MPG's than Acura seeing as Acura has No V8's or truck based SUV's! Lexus has several of each. They are better than Saturn (I know they aren't competitors) who only has a few V-6s and mostly 4's. I'm skeptical, having had an ES in my household in the late 90's that got awful MPG's, but good for them :) . . . and buyers if they get that mileage. :)

Broq

Broq,
That's because sales are weighted in. Lexus sells a lot more ES than LX570s for example. They also have hybrids, which Acura does not.

ralphie

Lies, damn lies, and statistics.

What kind of voodoo are we talking here??

How does rolling in SUV mileage numbers with sedan mileage numbers and sales numbers for both, come up with a number that has any meaning what so ever in relationship to the vehicle I am looking to buy?.

I'm not buying Honda as a whole, I'm buying a Civic or an Accord.

This is right up there with the days to sell data.

Ralphie,
It doesn't tell you what an accord is. The EPA does that. It tells you what Honda's lineup as a whole's average fuel economy using EPA figures is. Unlike CAFE which uses real voodoo economics, e85 loopholes etc.

ralphie

Again what purpose does this number server?

How does it help me buy a vehicle?

While the numbers posted on a Civic windshield aren't completely accurate, how does the number you provide for Honda relate to that car for accuracy?

Should I shy away from buying a Chevrolet Aveo because the Chevrolet line has a miserable True Mileage rating?

Should I buy a Toyota FJ Cruiser because their True Mileage rating is second best?

I am trying to understand what these numbers mean to me as a consumer and how they would be used to make a purchasing decision?

A great exercise in mathematics but don't see the use for the data.

Because the government and your elected officials are telling you cars will get 35 mpg in a few years, and they simply won't. You as a consumer will expect all cars to get 35 mpg and in reality they'll get much less.

Ralphie,
We do admit it will not help you make up your mind on which vehicle to buy today. You are correct.

Of course we never said it would.

Amuro Ray

The data itself is very useful, if you use it as a scientific "observation" - well, sort of. With the data, one can see how far off each manufacturer is away from the new (future) 35 mpg standard. With Asian manufacturers, especially Honda, that figure is "reachable" if they decide to have more small cars, or use hybrid engine for the Fit, for example, and drop the Ridgeline in the future. OTOH, for domestics, it'll be tough, because of the heavy emphasis on suvs & trucks. Think of it this way. Big trucks and suvs pull down mpg. EVEN if domestics uses hybrid engines in all their trucks and suv (and I an't talking 'bou those over 6000 lbs with the exclusion there), the best mileage they can get is about 20 mpg. That actually pulls DOWN on whatever mpg they have on their cars. Thus, putting 2 and 2 together, they actually need cars that achieve almost 50 mpg in order to balance out the trucks/suvs...sthg easier said than done!

sam

What I find interesting is the very poor mileage from all the "luxury" brands.

Acura - 20
Lexus- 21
Mercedes - 19
BMW -19

It seems that, when people yell about "gas guzzlers", the luxury brands escape that rep - inappropriately.

AR,
Actually these numbers don't show how far away the manufacturers are from the new 35 mpg rule. That's kind of the point. That rule is based on CAFE, not real world figures like we used. CAFE uses very confusing math including exemptions for E85 and other vehicles. The CAFE formula can also be changed at any time. If they had based the 35 mpg on real numbers like the EPA produces no manufacturer would be able to meet it.

Keith

In response to AR's comment, I was under the impression that 35 MPG was not an aggregate fleetwide average target like it is calculated today. I thought that a defined vehicle footprint would have a specific target to meet thus eliminating the practice of balancing out trucks and SUV's with econo-cars. Does anyone else have more info on the new regulations that can clarify?

Amuro has a good point, but if you think about the fact the the domestics Do have tons of trucks and big SUV's in their line ups and they are still only 4 to 5 mpg's behind the brands that do not have them. The way the market is shifting to cars, and most of the automakers are following suit, it doesn't seem all that impossible that domestics will be able to meet cafe- especially since there is some type of sales fugure equation. If people buy less trucks and SUV's, they will make less- which they all have already started doing. I think this would push Toyota above Honda on this list too.

Broq

Keith,
It's literally a 400+ page document that states they don't even have the methods to calculate the avg fuel economy in place yet!

Maybe whoever is in charge in 2011-2015 will use our math!

But trucks and cars will be counted separately.
Here's the link
http://www.nhtsa.dot.gov/portal/site/nhtsa/menuitem.43ac99aefa80569eea57529cdba046a0/

ralphie

So if trucks and cars are going to be dealt with separately why have you rolled them into these numbers?

Why didn't you run the math on each grouping and show a more realistic view of how close the manufacturers are to reaching the 35mpg goal?

You tried to make a point of how far away they are from reaching the goal and skewed the numbers by combining trucks and cars.

Keith

Ralphie,
They are not trying to make a point, they are not trying to prove something. They have just provided us with a set of data solely for informational purposes only.

Ralphie,
The biggest complaint with the new rules was the separation of trucks and suvs from car sales. Many wanted combined. Since we see a huge downturn in truck and suv sales and most automakers agree that's here to stay, there isn't as much a need to keep them separate.

DL

one important line in this post:

"...if automakers advertised them, few people would think any of them are really fuel-efficient ..."

if a manufacturer makes a vehicle that gets 11 mpg, it SHOULD drag down the fleet average. it should not matter what name you call it -- truck, SUV, crossover, ugly hunk of metal ... don't try to protect these greedy companies by trying to separate out certain vehicle types. people should look at these numbers and wake up to reality, pressure car makers to make more efficient vehicles (i think people are doing a great job making SUV prices & sales numbers plummet, whatever our motivation might be for not buying these stupid things)

We've been driving the Toyota Scion XB 2008- the boxy one the kids call the "Toaster" since purchase in June 2007. We report 27.2 average mpg. We love this car! YEah it's really 2008 bought in 2007...the manufacturer skipped a model year.

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