As part of our just-released $25,000 Compact SUV Shootout, we took the six contenders on an extended drive route of roughly 200 miles to test how efficient they truly were.
In the end, it wasn't a surprise that the highest EPA-rated vehicle won. The 2013 Mazda CX-5 is rated 26/32 mpg city/highway and 29 mpg combined. In our testing of mixed city and interstate roads that slightly favored highway speeds, the CX-5 returned 32.8 mpg. The next closest as well as only other compact SUV to best 30 mpg was the Honda CR-V at 30.3 mpg.
In the past we've often used the mileage computers as the basis of our scoring with the pump calculations as backup. We've written that today's modern trip computers can be more accurate than trying to do the math on a fill-up at the pump.
This time around we were glad we had the pump calculations to fall back on because while most trip computers were off by less than 1 mpg, the Mazda CX-5 was off by 2.7 mpg. That's nearly twice the number of the next worst offender, the Hyundai Tucson, which was off by 1.4 mpg.
Before our trip we topped off all the vehicles at the same pump at a downtown Chicago gas station. After the trip we returned to the very same pump to fill up the cars.
And yes, all the trip computers showed more favorable mileage than the pump estimates.
We contacted Mazda about the discrepancy, and the automaker's representatives explained the 8% difference between readout and calculation is somewhat normal. During their own tests, they ran 24 identical mileage runs in California and used the same gas station; Mazda's average discrepancy was 3.2% versus our 8% difference. After four of their runs, Mazda encountered more severe differences between calculated mileage and the trip readout than we did.
Why? Mazda points to variations in the pump sensitivity and the tank size, but that doesn't explain why the other vehicles in our test weren't as severely impacted.
In case you're curious as to which crossover had the most accurate trip computer, it was our winner, the CR-V, which was off by .3 mpg.