There’s only one sensible way to order the 2010 Kia Optima: with the standard 2.4-liter four-cylinder engine. It makes a healthy 175 horsepower, while the optional 2.7-liter V-6 makes just 194 horsepower. With the V-6 a bit heavier, the difference between the two engines is virtually indistinguishable.
But seriously, neither engine is going to provide much excitement, and most reviewers make that abundantly clear.
Autoblog mentions that a number of mid-size sedans offer larger, more powerful V-6 engines and calls it "still underpowered in our book.” Car and Driver says the Optima has "Joe Average performance," and ConsumerGuide warns that the Kia Optima with the four-cylinder engine "strains to provide highway passing power." Edmunds, like TheCarConnection.com, advises shoppers to go for the base four-cylinder engine “as it provides fully adequate performance while keeping the price tag and fuel consumption low."
A five-speed manual comes standard on the four-cylinder models, but a good five-speed automatic transmission is standard on the V-6 model and available with the four. Overall, most reviews don’t rank the popular automatic transmission very well. ConsumerGuide finds that "with either engine, the automatic transmission's upshifts are occasionally lazy and downshifts can be tardy,” while Edmunds says that the automatic “is reluctant to downshift.” However, the automatic does include a manual mode.
Kia clearly favors comfort over performance in tuning the Optima, though it handles well enough for most commuting and shuttling needs. In addition to their price and fuel economy benefits, four-cylinder models ride and handle slightly better than those with the V-6, in the experience of TheCarConnection.com’s editors. ConsumerGuide says that the Kia Optima is "no sports sedan” but calls it “a bit more athletic than the similar Hyundai Sonata."
Kelley Blue Book details that "body roll is minimal and the Optima enjoys a balanced feel," while Edmunds comments that the Optima is "no hot rod, though its responsive suspension and steering make it reasonably fun to drive around town." However, Edmunds notes, "driven aggressively on back roads, the Optima loses that sporting disposition." Car and Driver appreciates the Kia Optima's "good road manners," but warns that the Optima's "sporting pretensions [are] still only pretensions...there is nothing in its persona to tempt enthusiasts."
The 2010 Kia Optima is good but not great in terms of fuel economy. The Optima four-cylinder will get 22 mpg city and 32 mpg highway with either transmission, according to official EPA estimates, while the V-6 returns 20/28 mpg.