I made this video to point out the location for the unlimited points glitch on the city map.
All Credit for the original guide goes to RudeN4t3d4w6.
Make sure you save the game (options menu) at approx. 990 miles, load your last save and then just drive the last 10 miles.
Hope it helps
UPDATE:
Glitch also works for the RUS & JP version of the game.
The Explorer achievement in Mafia II (EEU) worth 26 pointsDrive a total of 1,000 miles in vehicles in "Jimmy's Vendetta." The Explorer achievement in Mafia II (JP) worth 15 pointsDrive a total of 1,000 miles in vehicles in "Jimmy's Vendetta."