We've got DS in his maxi rider behind the driver seat and DD's car seat (still in the reverse position) behind the passenger seat.

Aside from the fact that this recommended to be done this way - we wouldn't be able to put the baby seat behind the driver, as my husband is really tall (6 foot 7) and wouldn't be able to put the seat all the way back where he needs it to because the car seat would get in the way.