I know that some bus companies put a weight limit on drivers as I remember this TV programme in the UK ('Fat Families') as the dad had to shed weight to comply with an EU ruling:  http://www.eastbourneherald.co.uk/news/local/eastbourne-fat-family-set-for-tv-debut-1-1431401  Obviously that does not apply to private cars so inevitably there will have been accidents (perhaps even fatal ones) that have been due to car drivers being unable to brake or steer as quickly as they might have done without being hampered by a huge gut.   Today I learned that thin privilege is having quick reflexes to prevent you and others from harm