I also remember that the cars back then had much wider seats, where you could easily lay down ad get some shut-eye if needed.
It was also handy in other ways and I sometimes think that the narrow seats in today's cars have something to do with the decline in population of some areas, especially in the midwest (Iowa) where I grew up.
My first car was a 56 Olds-88 and those big seats sure did come in handy --- but it wasn't for shut eye. ;~))