Starting in 2008 Hot Wheels began using base codes. These base codes can be interpreted as follows.
Letters = Year of Manufacture
| A | 2008 |
| B | 2009 |
| C | 2010 |
| D | 2011 |
Numbers = Week of the year
| 1-52 | Week Of the Year |
Example #1: B12, B indicates the car was manufactured in 2009. 12 being the 12th week of the year puts the production date approximately the end of March.
Example #2: C47, which consists by a foremost transport aircraft, the Dakota or Skytrain.
Other then helping to search for new variations, These base codes have little meaning among collectors.