I just noticed this stat on the Social Club pages under stats/vehicles.
I don't know exactly what the parameters are, whether brushing a guardrail counts as a "crash," but i was kind of surprised at my number, because I run into sh!t all the time.
14.27 miles (I must have gotten a Gresley to Simeon from Paleto Bay or something)
My second character:
Whadda you got?