I was just researching this issue a few months back. The middle seat is safest for infant car seat. When you switch to a front facing seat, then move it to the side. The latch system on the LCI E70 X5 is only for the two side seats, not the middle. The seatbelt is used when securing the middle infant car seat. Seatbelt and latch are both just as secure, latch is easier since it simply latches on to the anchor points whereas you'll have to tug and snake the seatbelt through the holes. Once that's done, I just leave the base on there so I don't have to keep doing it. The latch does click onto the inner latch anchors from the two side seats, but I didn't do it since it wasn't approved for that and I'm not taking the risk. Only use seatbelt or latch to secure car seat, never use both.