car back seat measurements

Hi,
I need to buy a new car and I'd prefer not to buy something huge like a minivan or even an SUV. However, I have three car seats that need to fit in back. Each car seat measures 29 1/2 inches, which means that my new car's back seat width must be at least 60 inches. When I look on websites all I can find is back legroom or exterior back measurements, not the measurement of the width of the backseat itself. I now have a Volvo V70 (wagon) which has the 60 in. backseat, but the new models are smaller, w/backseats meauring only 56 inches. I don't want to buy new car seats, as I have Britax and love them. Please help me to figure out how to find a regular sedan-style car w/a back seat width of 60 inches or longer. Thank you, Kathy