Is this seat much wider than the frontier

Hi Mel, Thank you for your enquiry, the Highpoint Booster is from 52-54cm wide depending on the cup holders, if you have just one or both. We hope this helps. ?For further information on this or any of our other products available, if you follow the link https://www.babyonthemove.co.nz/store-locations/ this will take you to our online store finder. Here you can find contact details for your nearest Baby On The Move Store where one of our team experts will be happy to assist you in your product search and help answer any further questions you may have. We hope this has helped with your query.