Import automakers are risking their residual values to fill the void created as Detroit’s automakers reduce sales to commercial fleets and daily rental companies. Both GM and Ford have made very public pronouncements about their goal to reduce reliance on fleet business as part of their turnaround plans. Toyota, Nissan and Kia are waiting in the wings to make up some of the difference. One unintended consequence: the cost of renting a car is going up.