So, when a driver cooee's out to you at a bus stop from a car on a multi laned road....

"excuse me bloke, I am lost do you know where autobarn is"

I wouldn't nswer him because either:

 a) he is driving and will be out of earshot before I can give him directions.

 b) he has stopped and is obstructing traffic,

c) he has stopped and there is no other traffic on the road which would probably mean it is late at night - and I'm not about to get into conversataon with some random on a lonely road in the middle of the night.