OMG, I can't believe L is 20kg!

Car seats confuse me. I have W in an Evenflo Generations, it is harness up until 18kg and then used with the car seatbelt up until 45kg. So I am guessing that W will be at least 4 before he is out of the harness (which is no help to you lol). Then I think we use the car seat belt. But then the Australian car seat rules are very anal compared to NZ - we don't even need to have the seats anchored (but I do).