A moment of Silence for the fics I will never write

I'm being nitpicky in my fic tonight, especially about locations. (I  just finished playing around in google maps to find a significantly podunk town in the middle of Minnesota to set the fic, so that I could have it realistically close to Sioux Falls when the time came). Now Dean is asking a question about how far they are from Bobby's at this point (never mind that he's not driving at the point, shush 'tis a secret ) . My first inclination is to mention time. It's a standard thing around here, someone asks distance you automatically give the time. Halifax is four hours away, 3 if you have a lead foot lol.

You get the picture.

Now it's late, and I can't remember from the series if Dean and Sam have ever used this convention for replacing time for distance or if it's something completely Cape Breton-esque. 

Help?  Please?  I can easily state the miles but it sounds odd to me lol.