If you've got Isofix points in your car I'd really recommend the Maxi Cosi Priorifix (think it's pretty much the same as the Priori XP but also has a support pole that sits on the floor)....feels really securely fitted - I haven't actually tried it with the seatbelt though, but I've read some really good safety reviews on the Maxi Cosi ones, and Which did some independent safety tests and they did really well in those too x