CHICAGO – Kia Motors is adding a hybrid model to its Carnival minivan to meet increasing consumer demand for the technology and assist in meeting tightening federal fuel economy standards.Hybrids are a growing option for automakers as they strive to make vehicles more efficient and avoid costly federal fuel economy and emissions standards. They're also less expensive and a less dramatic adjustment for consumers who want to go greener but aren't ready to purchase all-electric vehicles.EV sales have been slow ...