# Convertible car seat overhang on vehicle seats and bases Which convertible car seats extend the least past the vehicle seat or the base? Britax Poplar S: The black base runners must rest entirely flat on the vehicle seat, and up to 3 inches \(7\.5 cm\) of the base may overhang the front in either orientation\. It is 17 in \(43\.18 cm\) wide and approximately 28\.5 in \(72\.39 cm\) long when reclined on a flat surface; installed length varies with the vehicle seat\. Britax Poplar \(anbbaby\.com listing\): The retailer lists overall dimensions of 20\.5 × 17 × 23\.5 inches and a 17\-inch design width\. On a flat surface, the seat is about 28\.5 inches long when reclined, but installed length varies with the vehicle seat and other factors\. Britax Poplar \(Poplar listing with vehicle fit notes\): The seat is 17 inches \(43\.18 cm\) wide\. It is approximately 28\.5 inches \(72\.39 cm\) long when reclined on a flat surface; vehicle geometry can change the installed measurement\. Three\-across worked best on full\-size outboard positions beside other narrow seats or low\-profile boosters\. The seat failed to fit a very small Sienna centre position and had questionable side overhang in an Odyssey centre position\. ### 1. [Britax Poplar S](/products/ucp/anbbaby-com/9925193335070) (sold by anbbaby\.com) The black base runners must rest entirely flat on the vehicle seat, and up to 3 inches \(7\.5 cm\) of the base may overhang the front in either orientation\. - Seat overhang: The black base runners must rest entirely flat on the vehicle seat, and up to 3 inches \(7\.5 cm\) of the base may overhang the front in either orientation\. (guide) - Width: It is 17 in \(43\.18 cm\) wide and approximately 28\.5 in \(72\.39 cm\) long when reclined on a flat surface; installed length varies with the vehicle seat\. (guide) - Reclined length: It is 17 in \(43\.18 cm\) wide and approximately 28\.5 in \(72\.39 cm\) long when reclined on a flat surface; installed length varies with the vehicle seat\. (guide) - Vehicle side overhang: - ### 2. [Britax Poplar](/products/ucp/anbbaby-com/8833528234270) (sold by anbbaby\.com) The seat is 17 inches \(43\.18 cm\) wide\. - Seat overhang: - - Width: The seat is 17 inches \(43\.18 cm\) wide\. (guide) - Reclined length: It is approximately 28\.5 inches \(72\.39 cm\) long when reclined on a flat surface; vehicle geometry can change the installed measurement\. (guide) - Vehicle side overhang: Three\-across worked best on full\-size outboard positions beside other narrow seats or low\-profile boosters\. The seat failed to fit a very small Sienna centre position and had questionable side overhang in an Odyssey centre position\. (review) ### 3. [Britax Poplar Convertible Car Seat](/products/ucp/anbbaby-com/9925032968478) (sold by anbbaby\.com) The retailer lists overall dimensions of 20\.5 × 17 × 23\.5 inches and a 17\-inch design width\. - Seat overhang: - - Width: The retailer lists overall dimensions of 20\.5 × 17 × 23\.5 inches and a 17\-inch design width\. (guide) - Reclined length: On a flat surface, the seat is about 28\.5 inches long when reclined, but installed length varies with the vehicle seat and other factors\. (manual) - Vehicle side overhang: - Every value in the table is a fact RoboTrunk checked, linked to the page it came from\. A dash means no checked fact fills that cell\. Prices and stock change, so this page prints neither: each product name links to its RoboTrunk page, which shows them live\. Written 2026-10-21T00:34:14.165Z. This page is published by RoboTrunk, a store built for shopping agents. The store named on this page sells the product and ships it. RoboTrunk is not the seller and never holds the money. Buying works in one path. RoboTrunk's tools prepare a checkout at that store, then hand back a short-lived link. The person approves the total; once RoboTrunk has checked the store's total against it, the person is given the checkout link to tap in their own browser, or, if the person prefers and gives permission, their agent may open the link and finish there, and payment always happens on the store's own checkout page. RoboTrunk never takes the payment or sees a card. Where the rest of this site is: - /agent/story.md is what RoboTrunk is and how it works, in full. - /agent/tools.json is every tool, its arguments and its answers. - /agent/merchants is every store you can buy from through RoboTrunk. - /products/ucp is every store's indexed products. - /products/search is one search across every store, in plain words. - [What RoboTrunk is](/agent/story.md) - [Every tool, in your browser through WebMCP](/agent) - [The tools and how to call them](/agent/tools.json) - [The stores you can buy from](/agent/merchants) - [Every store's products](/products/ucp) - [Search every store at once](/products/search)