Yeah, I can see how thats a bit unclear. The intent is that the range increases with each tally. So if a car had 3 tallies, X would be 1-3. a car with more tallies than its dice size is totaled (ie better find a new ride).
This is great input, Ill reword that in a future update!
Tally marks could be cleared by taking the car into a mechanic, which would cost Fuel points per the GM's discretion .