This achievement requires completion of 25 events at night in any game mode. A night race is a race where your car begins with its headlights on.
The time of day for a race is determined by a 24 hour military time type scale. For example, a race with conditions Clear Sky - 14h is equivalent to a 2 pm start time.
Races that are listed as 22h or 23h will always be night races, and are the safest choices for guaranteed progress. In my experience, races listed as 19h or 20h start in dusk and the car's headlights are not on at the beginning.
This achievement will come naturally in V-Rally career mode, as a certain percentage of races during the career will be night races
However, progress can be made more quickly in Quick Game or Multiplayer modes. Simply choose a short track, and make sure when selecting the track conditions that 22h or 23h is selected. If you are the lobby leader in multiplayer, you can bundle this progress with other multiplayer achievements. This achievement does track on the XBox, and you will receive 4% progress for each race completed
Personally, I used Quick Game - V Rally Cross - Mount Rainier USA - Track 1 - Clear Sky 22h. A six lap race lasts just over 3 minutes.