In my opinion, center installs with seatbelt are not safe due to the seatbelt being off center and the buckle strap being 6" long. I installed the Combi Coccoro via latch behind passenger seat. Using latch in the center is safer if your car seat is approved for non-standard spacing.
http://thecarseatlady.wordpress.com/...cocenterlatch/
http://thecarseatlady.wordpress.com/...ingcenterlatc/