Lost American

Two farmers were leaning over a gate in the Sperrins when this American pulls up in the longest Cadillac you ever did see.
'Pardon me, gentlemen, says the American, winding down the window, 'but could you tell me how far it is to O-magh.'
'Well now,' says one of the farmers, 'it would be the best part of fifteen miles from here. But in a car like that you should do it in ten.'