10 Best Narrowest Car Seats And Boosters 2019 [+Buyer Guide] 1 5 years Overnightmedicines.com Top rated narrow car seats and boosters for infants, toddlers and 4 years old and above. Safety 1st grow and go for newborns, Maxi Cosi Mico Max 30 for 1 year and above, and Diono Radian RXT for 4