I just came across this thread and noticed more than one person has had trouble when clearing immigrations in Canada. I too, have had problems in Canada but not even due to mileage runs. I often travel there alone for pleasure. This too, causes numerous hassles and triggers baggage searches and numerous questions. They even want to see my cash and credit cards to make sure I'm not a vagrant or something.
Next time I go to a city in Canada by myself, I'm going to first go online and see what the destination city has to offer while I'm there. Then when questioned, I can say I'm going to the baseball or football game, a festival or to some of the museums which by then, I'll know all the details.
[This message has been edited by Neal (edited Mar 07, 2004).]