Bmw I3 Boot Liners Available Here. Sports utility vehicles are used for more than just sport. The same vehicle that transports wood and gravel may be used later in the day to haul kids to ballet practice. Boot liners are used to provide additional protection against wear to cargo areas that are just carpeted. The liners are specifically designed to fit each make and model and include a raised edge meant to trap dirt and liquid. Boot liners come in several varieties with different features so think about the type of coverage that you need to make sure that you choose the best liner for your car.