Fleets got a chance last week to gauge where they stand with their trucks' mpg based on benchmarking data gathered from customers of analytics firm Vusion. Other factors fold into and modify the mpg equation, according to the company, and fuel economy information from trucks shouldn't always be taken at face value.

The company, which is owned by Trimble, discussed mpg benchmarking for fleets Tuesday, Aug. 25, at its sister company PeopleNet's User Conference in Phoenix. Vusion incorporated customer data by freight type, measuring fleets' mpg in benchmarking groups of truckload dry van carriers, flatbed carriers, less-than-load (LTL) carriers, refrigerator and tanker trucks.

Each group had between eight and 12 companies included and an average fleet size of 250 trucks with either 13L or 15L engines, according to Vusion, and 95% of the trucks included were company-owned. The data set presents "physical mpg" calculated from fuel purchases and odometer readings for each particular truck.

Also, outlier data — measures at the extreme upper or lower ends of the group — were excluded, "because we don't want to have any weird data," said Anne Heitkamp, a Vusion statistician. "So we cleaned that up."

The benchmarking data span a three-year period from the second quarter of 2012 to the second quarter of 2015. At the start, the average fuel economy of all the fleets studied was 6.44 mpg, which climbed to 6.99 mpg at the second quarter of 2015.

"MPGs are on the rise. From quarter two of 2012 to quarter two of 2015, MPGs are up 8.5%," said Vusion President Thomas Fansler. "That's a remarkable increase." However, that's only the broader, aggregate picture, he noted, discussing a number of factors fleets should be aware of that affect what their expected fuel economy should be.