Americans - unlike their cars - are getting wider every year. Unfortunately, carmakers aren’t keeping up with the nation’s spreading waistline, especially when it comes to their seats, and passengers are starting to feel the pinch. That’s why at this year’s Detroit Auto Show carmakers were showing concepts fitted with seats that are more like chairs rather than the sports-buckets, which dominate most production cars today.

A recent survey comparing the seat widths of several used cars with those of vehicles on display in Detroit revealed that much hasn't changed over the past decade, reports The Detroit News. Seat widths and the thickness of their padding remains much the same now as it was back in 1999, averaging around 20in in width.

Most carmakers today design seats with outside suppliers, one of the largest of which is Johnson Controls, which has a laboratory dedicated to the study of the human form. One of the most recent innovations developed by the lab is a new foam, which is thinner than previous designs, but provides more support. The seats are "designed both to be more forgiving and comfortable for the larger occupant," a spokesman explained.

This is all well and good for mainstream models but if you’re in the market for an exotic and your body isn’t in the best shape it could be, you’d better be prepared for a tight squeeze. Most of the cars from makes such as Lamborghini, Maserati and Ferrari do offer varying seats sizes. Unfortunately, the largest of these stretches just 18in across.