Car seat with fixed base

The invention relates to a child safety car seat being installed in a vehicle in combination with a fixed base. The fixed base is secured to the vehicle by way of the adult seat belt and is supported by a support leg to the foot well. The Child car seat is secured to the fixed base by an interlocking means achieved by inserting the child seat generally from a sideway direction. The advantage of this solution is that the dynamic strength and integrity of the interlocking of the car seat and the fixed base is not dependent on typical latching solutions, which cannot always being guaranteed to have fully engaged.