There are no dedicated anchors for the latches in the middle seat (not talking about the rear anchors for the over-the-seat tethers), I was pissed I found this out after I bought my E70 so I had to put my youngest on the sides. Now they're older and in full Recaro forward facing seats...

But even if you chose to use the middle seat most anchor/latch straps will not reach to the inner most anchors...