They could try every possible combination. However, one of the main problems is that with all of those combinations, I would bet a weeks salary that there is more than one vehicle matching the color/basic description (eg- dark sedan, red pickup, etc) within those possible combinations.
And that's if the robber had the plates actually belonging to that car on the car at the time.
Pittsburgh Pirates- 1st place NL Central 7/15/11
They've got us surrounded? Good. Now we can fire in any direction, those bastards wont get away this time
An amateur will train until they get it right. A professional will train until they can't get it wrong.