In May, the EPA's FuelEconomy.Gov site listed three sets of initial fuel economy figures for the 2021 Kia K5, a move that helped confirm the end of the Optima name. The EPA has fiddled with the data set since then — the site doesn't list an all-wheel drive K5 anymore, for instance — but Kia has done us the favor of providing complete mpg numbers for every K5 trim except the flagship GT. The entry-level K5 LX with front-wheel drive gets 29 miles per gallon in the city, 38 on the highway, and 32 combined. This lines up with a model on the EPA site that's listed with stop/start on the 1.6-liter turbocharged four-cylinder. Most notably, the K5 LX sips a lot less fuel than the entry-level 2020 Kia Optima LX. The Optima LX houses a 2.4-liter four-cylinder with 185 horsepower and 178 pound-feet of torque — five horses up but 12 lb-ft down on the K5 — and gets 24 city, 32 highway, 27 combined. And the K5 only costs $100 more than the Optima.
Among the competitive set, the in-house rival Hyundai Sonata in entry-level SE trim gives up one mile per gallon in the city to the LX, otherwise the two are equal. The Sonata SE, though, gets motivated by a 2.5-liter four-cylinder with 191 hp and 181 lb-ft. The Sonata SEL Plus with the same 1.6-liter as the Kia but costing $4,000 more returns 27 city, 36 highway, 31 combined. Outside the fold, the Toyota Camry ultimately evens out the fuel economy score in delivering 28 mpg city, 39 highway, 32 combined. The Honda Accord edges all comers with 30 mpg city, 38 mpg highway, and 33 combined thanks to its continuously variable transmission; the other three shift through eight-speed automatics.
The front-wheel drive K5 LXS, EX, and GT-Line all return 27 mpg city, 37 mpg highway, and 31 mpg combined. The figures match a K5 model on the EPA site that omits the stop/start system on the 1.6-liter, but we can't see where Kia has mentioned a stop/start system in its K5 release materials. About 100 pounds difference in curb weight covers all four trims that we have info on so far. This would appear to indicate the lack of the fuel-saving tech on the three trims causing slightly lower fuel economy as opposed to extra luxuries weighing matters down.
Only two trims for now come with the option of all-wheel drive, the LXS and GT-Line. When the K5 GT arrives, it will only come with all-wheel drive. Check the box to send power to all the wheels, and both variants deliver 26 mpg city, 34 mpg highway, 29 mpg combined. The Camry SE AWD comes closest to the LXS, mustering 25 city, 34 highway, and 29 combined, whereas the higher-trim XSE cuts combined mileage to 28 mpg. Among the other AWD entries in the segment at this price range, the Nissan Altima S AWD gets 26 city, 36 highway, 30 combined, the Subaru Legacy AWD with the naturally aspirated 2.5-liter returns 27 city, 35 highway, and 30 combined, both of those options shifting through CVTs.