The VINs are robotic cars who were made at the Motor Co. Factory in Autovia.

In the cut-scene for Off Road Race 2, lots of students from the Chick Hicks Racing Academy went into the Motor Co. building, and came out as VINs.

They appeared in a lot of races that happened after that.

The only location that they didn't appear in was Santa Carburera, and VIN means Vehicle Identification Number.