While the Kia Carnival with its V6 engine has been called out for not being a very fuel efficient vehicle, hybrid minivans like the Toyota Sienna remain a formidable force in offerings of efficiency over its competitors. In a time when fuel economy and environmental concerns are important to many consumers, the Carnival's relatively thirsty engine has become something of a cause célèbre. The fuel economy disadvantage is a significant draw back in a family vehicle that will see frequent use, claims some; others argue that the power and smoothness of the V6 trumps the economy. But there's also talk of whether Kia should offer a hybrid powertrain option to further compete with eco friendly alternatives. The Carnival's fuel consumption is a feature that potential buyers frequently weigh against other features and benefits of the car; and then there are debates about priorities in choosing a family vehicle versus long term ownership costs.