Think the buckle thing might be on seats for older kids.
Amy's 10 months now and has just moved on from her first seat. We got a seat and buggy that it will clip into from Mama's and Papa's. Still using the buggy but without the clip in set now and occasionally use the seat in other vehicles than normal. The clip in system is a god send.So easy to get her in and out of the car (whilst asleep), and no messing with straps everytime. We also got a spare base so we could have one in Alison's car and one in my truck, which was probably a bit lazy but well worth it.
Can't remember the brand we have now but its exactly the same as one of the recaro ones just without the label, made by the same people, forward facing and seems a good fit, in all the vehicles we've tried. Maverick, Subaru Impreza, Renault Master.