I know of a guy who drives his 400lb fat *** self in a 1995 Hyundai.. super super small car. I'm sure you can make it work somehow. They probably won't break the seats, but the cushioning will definitely never be the way it was before. Especially if you have these fat girls in your car continuously. I would call the manufacturer and ask them what the weight limit is for your seats. I would say the average fat girl weighs about 200-250lbs. If she's like a whale, maybe pushing closer to 300lbs. Also make sure that your tires are filled with an appropriate amount of air. That will be way more important than the car's size or seats.....