The obesity epidemic that seems to be engorging the western world has created a new problem: people are getting too fat for their cars.This isn't a matter of being unable to get into the car, either. According to a report in USA Today, American government guidelines on the maximum weight that a car can carry can easily be exceeded before any luggage is even added.The guidelines came in in 2006, partly as a result of the 2000 Firestone tyre recall. Some of the blame for the failure of the tyres – which resulted in many roll-over crashes – was laid with overloading. Consequently, car manufacturers added a maximum weight limit for their cars. In the US, these limits have generally been calculated using an average passenger weight of 150lb – which is 68kg, or almost 11 stone. Even in the EU, the average driver weight is taken as 75kg.According to USA Today, that means that two-seat sports car such as the Corvette C6 and Mazda MX-5 (max capacity 340lb, 155kg) aren't certified to carry two 200lb (90kg, 14 stone) adults.It's not just sports cars that are a problem, either. Apparently, most five-seaters, such as the Honda Accord, are rated at 850lb (385kg), so five 170lb (77kg) adults would fill the car to their limit, before any luggage.Before any of our British readers start feeling smug, it should be pointed out that obesity is a rapidly growing problem over here (pun intended). Car makers work hard to shave those valuable few kilos from their cars' kerb weights, making the handling sweeter and the emissions lower, but it's all wasted if we get a bit too fond of pies.