Sometimes we get letters from readers asking for advice, or criticizing our reports on gas mileage.

We're always happy to hear their experiences--but a bit of perspective is sometimes needed.

Reader Marcus Witte recently sent us the following note (we've edited it slightly for clarity):

Your review of the Honda Civic Ex sedan automatic mpg gas mileage is false and, so far, presentation of the information is at best misleading in the state of California.

2013 Honda Civic EX-L

2013 Honda Civic EX-L

I have almost 5,000 miles on a 2013 Honda Civic EX and I have yet to average 29 miles city and highway. I have used the car's on board computer which seems to inflate the actual mpg and then manual calculations of what I filled the tank in number of gallons to cross check.

While I like the Civic, my main reason for buying the gas-only model versus the hybrid was that the gas model was supposed to get 38 mpg.

When I asked the Honda sales and service folks what was going on, I get mixed messages. One said: Wait until the engine is broken in.

Then when I brought the car in for an oil change, the service manager told me cars sold in California never get the MPG presented on the sticker and even less in the winter months, because of our clean-air policies [which require a different blend of gasoline in the winter].

Witte is clearly unhappy with his Civic's gas mileage, which is understandable.

But there's some context missing, and his note seems to be a perfect case of the maxim, "Your mileage may vary."

Here's how we responded:

Thanks for your note. I fear you may have overly high expectations for the gas mileage of the car you bought.

2013 Honda Civic EX-L

2013 Honda Civic EX-L

The 2013 Honda Civic with the automatic transmission is rated by the EPA at 32 mpg combined (28 mpg city, 39 mpg highway). When you write, "the gas model was supposed to get 38 mpg," that appears to be its highway rating--which you would only achieve if you covered all your miles at highway speeds of about 65 mph.

Unfortunately, carmakers often advertise the highest of the three ratings (the highway number), with the number shown very large and the "highway" qualifier very small. Some shoppers miss the qualification, and assume the car gets that gas mileage under all circumstances, which it won't.

I presume you're driving the car in mixed use--around town, some city traffic, some highway miles--so you should expect to average the *combined* rating of 32 mpg.

You say you're getting 29 mpg, or about 10 percent lower than 32 mpg--which is within a reasonable margin of error.

That said, the EPA website for your model shows that 12 owners submitted real-world gas-mileage readings that average 35.1 mpg. Similarly, Fuelly shows (across both manual and automatic Civics) an average of 35.0 mpg. So you're considerably below those reported real-world averages.

In general, as we've written, some makers vary more from their EPA ratings than others. Honda does well, whereas Ford products consistently underachieve.

As for your dash computer, Edmunds found that the average dash computer is 5.5 percent optimistic--but those from some makers are considerably worse.

2013 Honda Civic EX-L

2013 Honda Civic EX-L

To sum up, it sounds like you're getting gas mileage that's a bit lower than the combined rating, and lower than the reported real-world mileage from other owners.

The three factors that most affect mileage are (a) driving style; (b) mix of city and highway use; and (c) temperature.

For driving style, if you're aggressive--accelerating hard, using the brakes a lot--your mileage will be worse. Perhaps try driving as if you have an egg between your foot and the accelerator--accelerating gently, planning ahead so the car can coast down to stops--and see if that makes a difference?

What is your mix of city and highway miles? If you're using the car largely for low-speed stop-and-go, with lots of stopping, accelerating, and braking, it'll do worse than if you lock it into cruise control at the legal highway speed limit.

Finally, if you live in a place with cold weather, that reduces mileage compared to temperatures of 70 degrees (low enough so you don't need to use the air conditioning, which also reduces gas mileage).

Hope this helps.

What do you think? Were we fair in our response?

Leave us your thoughts in the Comments below.


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