Most automobiles overstate fuel economy, study finds

Mileage is an important factor of an automobile that practically all drivers keep in mind. Because it affects everything from the performance of a vehicle to its sticker price, fuel efficiency is not something you should glance over, and that makes tracking the mileage incredibly significant. The emphasis on fuel economy may be great, but all drivers need to be wary of putting all their faith in an automobile's report. 

Mileage meters are not always accurate
With all eyes on the fuel efficiency, many drivers look to onboard meters for help tracking mileage. However, these digital readouts are not as effective as most motorists would like them to be. Instead of providing drivers with a glimpse of a vehicle's actual efficiency, many of these computerized displays overstate the true number of miles per gallon an automobile is achieving, The Detroit News reported. 

"I don't think anyone is trying to hoodwink anybody," Dan Edmunds, director of vehicle testing for automotive research firm Edmunds.com, told the news source. "But these meters have never been 100 percent accurate. They are more for instantaneous feedback to let you know how you're doing." 

Edmunds.com regularly tests models to find the average miles per gallon rating and compare it to what the manufacturer claims the average is. Testing in 2010 found that some of the worst offenders had mpg readouts that inflated fuel efficiency by as much as 19 percent, the news source reported. On average, cars boasted a fuel economy that was about 5 percent better than the actual results. Although this may not seem like much, it can make a big difference in fuel costs or maintenance issues throughout the life of a vehicle. 

PickupTrucks.com noted a similar trend during their 2013 Light-Duty Challenge. Results of this review showed five of the six trucks examined reported better fuel economy than what the real-life testing found.  

Watch the dashboard counter
Some drivers may trust their vehicle enough to ignore the dashboard meter, but this would be a mistake. For one, the mileage provides important insight into when vehicle maintenance is needed. It also allows owners to keep track of how much money they are spending on fuel, check if all systems are working properly and project what they need for longer, off-road driving trips. 

Drivers of some newer trucks may have less to worry about. According to Edmunds, early testing on the 2014 Chevrolet Silverado, which recently topped Consumer Reports' list of the best pickup trucks, features a mileage tracker that is only off estimates by about 2 percent. That is below average - good news for drivers on the hunt for a future off-road vehicle. 

What you can do
While tracking your own mileage may be manageable, it is more difficult to adjust to the counters on a used model. That makes selecting a model with good ratings and a strong history of impressive fuel efficiency of paramount importance. Researching the average fuel economy of a certain model truck before purchase enables you to avoid any surprises, but writing down the readings of a tripmeter may be the most important of all. You should also be manually logging the number of miles you get out of a certain amount of fuel.

"The only way to get a real accurate reading is to keep log books," Edmunds told The Detroit News. "You need to record your trip odometer and the fuel amount that you used."

Still, even registering the numbers yourself is not a fool-proof way to estimate fuel economy. Variables such as where you are driving, what the weather is like and whether or not you are off-roading can impact the bottom line.