CARS.COM — The Kia Optima was the big mpg winner in our 2016 Midsize Sedan Challenge, averaging 36.1 mpg. The Volkswagen Passat took second with 33.7 mpg, more than 2 mpg behind the Kia. Rounding out the top five were the Mazda6 (33.3 mpg), the Nissan Altima (32.9 mpg) and the Honda Accord at 32.7 mpg. We calculated fuel economy results by averaging our fill-up calculations (trip miles divided by gallons pumped at the end) with each car’s trip computer output.
For the roughly 220 miles that we drove, each sedan returned an average speed of 45-46 mph, a brisk pace helped by stretches of open highway driving and little to no traffic along the street portions of the route. Because our average mph topped 45, you should really consider this more a comparison of highway mpg and not combined mpg.