2021 Kia K5 first drive: Name games dilute a fine follow-up act

The sedan formerly known as the Kia Optima gets a new look this year, but the change hardly stops at the body. It gets a new name too. The question we still have, after hundreds of miles spent in it—is the mid-size 2021 Kia K5 different enough to earn the new K5 badge? The Optima and K5 have as much or more in common than just about any...