You've read the reviews, and it's finally time: You're off to the dealer to replace your old car with a new, much more fuel-efficient vehicle.

But then you get to the dealer, and during your test drive, you notice that the gas mileage shown on the car's display is nowhere near the EPA rating.

Should you worry? Probably not.

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Let's say you're considering the new 2014 Honda Accord Hybrid, which was our 2014 Best Car To Buy. It has an EPA combined rating of 47 mpg (50 mpg city, 45 mpg highway).

2014 Honda Accord Hybrid Touring

2014 Honda Accord Hybrid Touring

It's a popular model of the new-for-2013 Accord mid-size sedan, and supplies are very limited right now as production slowly ramps up.

This was, in fact, exactly the situation faced by reader Aron Stern of Carlsbad, California, who wrote:

I just test drove two Accord Hybrids. The gas mileage displays - one on the LCD screen and one within the speedometer - both indicated in both cars gas mileage of between 27 and 32 mpg. Did the same thing happen to you?

I really need to know, or else I cannot buy the car!! My Prius display is optimistic by 5 to 10 percent at 48 mpg. Is the Honda display at 27 mpg equally optimistic? How can I conclude the Honda actually gets at least 40 mpg per tankful in real world driving?

Stern raises a good point: The mileage that appears on dealer demonstration vehicles may be very low.

But there are several reasons why that may be the case--and why you shouldn't worry too much about it.

Here's why, lightly adapted from our response to Stern:

Short test drives at the dealership really aren't representative of the gas mileage that a car will get in regular usage by an owner.

Test drives at dealers tend to take place with the car started from cold, which cuts efficiency. It may have been moved around many times on the lot without ever warming up, or it may have spent much of its life on multiple short 5- or 10-minute drives.

2014 Honda Accord Hybrid Touring

2014 Honda Accord Hybrid Touring

It's rare that dealers will let a potential buyer spend an hour or more behind the wheel, or put on 40 miles under a variety of driving conditions.

 

I'd suggest that you look at the crowd-sourced results for the Honda Accord Hybrid on FuelEconomy.gov, here (42.4 mpg averaged over 2 owners so far).

Unfortunately Fuelly.com doesn't break out the hybrid model of the 2014 Honda Accord separately, though we hope they will in future as more of them enter the roads.

FYI, we shoot for a minimum of 200 miles on test drives, preferably much more, for even the most basic assessment of real-world gas mileage for any car.

We found the Accord Hybrid to deliver real-world mileage of well above 40 mpg. Hope this helps.

So there you have it: When you're evaluating real-world mileage, don't pay much attention to the dealer demo car.

Instead, look at the reports on FuelEconomy.gov and at crowd-sourced mileage sites like Fuelly.com.

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