It's coming to mainstream seats though. Graco has had the Slimfit3 LX out for a couple years now; we had 6 (3-across in a Toyota Corolla and Honda Fit) and they worked great except for the kids not really liking them. Britax has the Poplar and One4Life Slim; Chicco apparently added the Fit3x when I wasn't looking.
It's coming to mainstream seats though. Graco has had the Slimfit3 LX out for a couple years now; we had 6 (3-across in a Toyota Corolla and Honda Fit) and they worked great except for the kids not really liking them. Britax has the Poplar and One4Life Slim; Chicco apparently added the Fit3x when I wasn't looking.