Well, seeing as I don't have the Trep anymore, I can't say for sure when my Trep was made, but just going by the first example where his '02 was made in Feb of '02, I had purchased my 2000 in September of that year, but I'll use the date of Feb of 2000. I wrecked it in Nov of 04 with over 155,000 miles so that makes it 4 year and 9 months old. For the sake of the argument, I'll just use 155,000 miles even.
155,000/57 months = 2719 miles/mo
155,000/57/30 = 90.64 miles/day
155,000/57/30/24 = 3.777 mph
Again, that's assuming that my car was made in Feb of 2000. If you went strictly by date of purchase, my speed would be 4.31 mph.