Yes, Sunshine Radian are the slimmest seats available. I have a small van and had to buy three of these in order to fit three across. I think I got mine on sale for about $250 each...they are not cheap. Also, make sure you have extra insurance for your car (call your insurance company to tell them you will be taking daycare kids in your car) in case of an accident. I am no longer driving with my daycare kids and trying to decide whether to sell my seats or to keep them in case I decide to drive again someday (like when my daughter goes to school and I can fit them all in the van).